# The Ultimate Pi Day is Over… Now What?

Today's post is from guest blogger Dan Seal who works in the MATLAB Product Marketing team here at MathWorks. Dan recently celebrated Pi Day on 3/14/15 and wanted to know what other holidays he might be able to celebrate in the future.

### Contents

Every year, mathematicians and their geeky cohort celebrate Pi Day on the fourteenth of March, a date whose written representation (3/14) looks like the first three digits of the mathematical constant pi (3.14). But this year’s Pi Day was extra special and generated additional buzz because when you include the year in the written date of 3/14/15, it gives us two more digits of everyone’s favorite irrational number. And if you were like me, you may have even marked the minute when it was 3/14/15 9:26, both in the AM and again in the PM.

But the opportunity to observe these additional digits of Pi on the calendar is something that comes around only once per century, so I don’t expect to see it again. This got me wondering if there are any other special dates I might be able to look forward to. M/DD/YY is not the only representation of a date, and Pi is not the only special constant out there with multiple digits. So I collected all my favorite mathematical and physical constants along with a slew of possible date representations, and threw them all into MATLAB to see what it would give me.

#### Starting small

I decided to start out with just two constants which I could use to test my work as I went along. I selected Pi and the square root of 2. Fortunately, MATLAB can calculate a very accurate approximation of these values, so I didn’t have to look up the digits.

names = { 'Archimedes'' Constant, or Pi' 'Pythagoras'' Constant, or Root 2' }; numbers = [ pi sqrt(2) ];

#### Defining the possible date formats

Next, I wanted to construct all the allowable date formats. I wanted to consider only dates that included the month, day, and year. However, I figure it could be a 2- or 4-digit year. Similarly, I allowed the month and day to each be 1 or 2 digits. And finally, I allowed the month, day, and year to be ordered in any of four different arrangements:

- the American version of month/day/year,
- the common standard outside the US, day/month/year,
- the common year-first version, useful for sorting, year/month/day,
- and for good measure, the alternate year-first arrangement, year/day/month.

MATLAB uses the datetime data type, introduced in R2014b to easily manipulate and format dates and times. Based on my formatting requirements above, I was able to build all the possible datetime format strings that would meet my criteria.

yearFormats = {'yy' 'yyyy'}; % 2 or 4 digit year monthFormats = {'M' 'MM' }; % 1 or 2 digit month dayFormats = {'d' 'dd' }; % 1 or 2 digit day availableFormats{length(yearFormats)*length(monthFormats)*length(dayFormats)*4} = ''; c = 1; for y = yearFormats for m = monthFormats for d = dayFormats availableFormats{c } = [d{:} '/' m{:} '/' y{:}]; availableFormats{c+1} = [m{:} '/' d{:} '/' y{:}]; availableFormats{c+2} = [y{:} '/' m{:} '/' d{:}]; availableFormats{c+3} = [y{:} '/' d{:} '/' m{:}]; c = c + 4; end end end disp(availableFormats')

'd/M/yy' 'M/d/yy' 'yy/M/d' 'yy/d/M' 'dd/M/yy' 'M/dd/yy' 'yy/M/dd' 'yy/dd/M' 'd/MM/yy' 'MM/d/yy' 'yy/MM/d' 'yy/d/MM' 'dd/MM/yy' 'MM/dd/yy' 'yy/MM/dd' 'yy/dd/MM' 'd/M/yyyy' 'M/d/yyyy' 'yyyy/M/d' 'yyyy/d/M' 'dd/M/yyyy' 'M/dd/yyyy' 'yyyy/M/dd' 'yyyy/dd/M' 'd/MM/yyyy' 'MM/d/yyyy' 'yyyy/MM/d' 'yyyy/d/MM' 'dd/MM/yyyy' 'MM/dd/yyyy' 'yyyy/MM/dd' 'yyyy/dd/MM'

#### Extracting the digits

The next task was to extract the digits from my numbers. I figured I’d be using some quantities with large positive or negative exponents, so my technique had to be robust to different types of numbers. I decided the best approach was to convert the numbers to strings using a consistent format so I could easily remove any decimal points and exponential terms. I found that `sprintf` with an exponential format could achieve this. Keeping nine digits after the decimal point ensured that I had enough precision to build even my longest date (which required 8 digits). The `char` and `arrayfun` commands allowed me to run `sprintf` on each number individually and then build it into a character array.

digitsStr = char(arrayfun(@(x)sprintf('%1.9e',x),numbers,'UniformOutput',false)); disp(digitsStr)

3.141592654e+00 1.414213562e+00

Next, I removed the decimal point and keep only the first eight digits, which is the most I will need.

digitsStr = digitsStr(:,[1 3:9]); disp(digitsStr)

31415926 14142135

#### Building the list of special dates

Finally, I built a loop to test each of my mathematical constants against all the possible date formats and see which ones could be constructed as real dates. I tried out each possible date format using a `try/catch` statement. If the date I tried to construct wasn’t a real date, I would catch that particular error. But if it was, it would be added to the list of special holidays to celebrate and the name of that constant would be recorded as well. I also specified a pivot year to define which century two-digit years belong to. Since I’m looking or future holidays, I decided that all two-digit years should represent dates sometime after 2015.

% Initialize arrays maxPossibleDates = length(numbers)*length(availableFormats); holidayDates(maxPossibleDates) = datetime; holidayDates.Format = 'MMM dd, yyyy'; holidayFormats{maxPossibleDates} = ''; holidayNames{maxPossibleDates} = ''; % Initialize counter c = 1; for ii = 1:length(numbers) %Consider each number for jj = 1:length(availableFormats) %For each number, consider each format fmt = availableFormats{jj}; testFmt = strrep(fmt,'/',''); strLength = length(testFmt); testStr = digitsStr(ii,1:strLength); try %If format is valid, add it to the list holidayDates(c) = datetime(testStr,'InputFormat',testFmt,'PivotYear',2015); holidayFormats{c} = fmt; holidayNames{c} = names{ii}; c = c + 1; catch err %If format errors, make sure it is the expected error if ~strcmp(err.identifier,'MATLAB:datetime:ParseErr') rethrow(err) end end end end % Trim empty values from end of lists holidayDates = holidayDates(1:c-1); holidayFormats = holidayFormats(1:c-1); holidayNames = holidayNames(1:c-1);

Because my dates are represented as datetimes, I can easily put them in chronological order with the `sort` function.

[holidayDates,ind] = sort(holidayDates); holidayFormats = holidayFormats(ind); holidayNames = holidayNames(ind);

#### Printing out the results

Let’s see how many opportunities there are to celebrate Pi Day or Root 2 Day.

for ii = 1:c-1 specialDate = holidayDates(ii); specialDate.Format = holidayFormats{ii}; fprintf('On %s (%s), we can celebrate %s Day\n',... char(holidayDates(ii)),char(specialDate),holidayNames{ii}) end

It looks like there are a few Pi Days we can celebrate over the next 30 years. And then there are some Root 2 Days to celebrate after that.

On Jan 02, 1414 (1414/2/1), we can celebrate Pythagoras' Constant, or Root 2 Day On Feb 01, 1414 (1414/2/1), we can celebrate Pythagoras' Constant, or Root 2 Day On Feb 13, 1414 (1414/2/13), we can celebrate Pythagoras' Constant, or Root 2 Day On Mar 21, 1414 (1414/21/3), we can celebrate Pythagoras' Constant, or Root 2 Day On Jan 04, 1421 (1/4/1421), we can celebrate Pythagoras' Constant, or Root 2 Day On Apr 01, 1421 (1/4/1421), we can celebrate Pythagoras' Constant, or Root 2 Day On Mar 14, 1592 (3/14/1592), we can celebrate Archimedes' Constant, or Pi Day On Mar 14, 2015 (3/14/15), we can celebrate Archimedes' Constant, or Pi Day On Jan 04, 2031 (31/4/1), we can celebrate Archimedes' Constant, or Pi Day On Apr 01, 2031 (31/4/1), we can celebrate Archimedes' Constant, or Pi Day On Apr 15, 2031 (31/4/15), we can celebrate Archimedes' Constant, or Pi Day On Jan 03, 2041 (3/1/41), we can celebrate Archimedes' Constant, or Pi Day On Mar 01, 2041 (3/1/41), we can celebrate Archimedes' Constant, or Pi Day On Jan 14, 2042 (14/1/42), we can celebrate Pythagoras' Constant, or Root 2 Day On Jan 04, 2114 (1/4/14), we can celebrate Pythagoras' Constant, or Root 2 Day On Jan 04, 2114 (14/1/4), we can celebrate Pythagoras' Constant, or Root 2 Day On Feb 14, 2114 (14/14/2), we can celebrate Pythagoras' Constant, or Root 2 Day On Apr 01, 2114 (1/4/14), we can celebrate Pythagoras' Constant, or Root 2 Day On Apr 01, 2114 (14/1/4), we can celebrate Pythagoras' Constant, or Root 2 Day On May 09, 3141 (3141/5/9), we can celebrate Archimedes' Constant, or Pi Day On Sep 05, 3141 (3141/5/9), we can celebrate Archimedes' Constant, or Pi Day On Jan 03, 4159 (3/1/4159), we can celebrate Archimedes' Constant, or Pi Day On Mar 01, 4159 (3/1/4159), we can celebrate Archimedes' Constant, or Pi Day On Jan 14, 4213 (14/1/4213), we can celebrate Pythagoras' Constant, or Root 2 Day

#### Generalizing to a larger set of inputs

Since this gave me good results, I could put the entire analysis into a function and then call it with a much longer list of my favorite mathematical and physical constants. What are the next holidays coming up? Be sure to mark your calendar.

names = { 'Archimedes'' Constant, or Pi' 'Euler''s Number, or e' 'Pythagoras'' Constant, or Root 2' 'Golden Ratio, or Phi' 'Root 3' 'Root 5' 'Speed of Light, or c' 'Avogadro''s Number, or N_A' 'Standard Gravity, or g' 'Gravitational Constant, or G' 'Planck Constant, or h' 'Ideal Gas Constant, or R' 'Coulomb''s Constant, or k_e' 'Elementary Charge, or e' 'Bohr Radius, or a_0' 'Electron Mass, or m_e' 'Proton Mass, or m_p' 'Atomic Mass Constant, or m_u' 'Boltzmann Constant, or k_B' 'Faraday Constant, or F' 'Stefan-Boltzmann Constant, or Theta' 'Standard Atmosphere, or atm' 'Planck Length, or l_P' 'Planck Mass, or m_P' 'Planck Time, or t_P' 'Planck Charge, or q_P' 'Planck Temperature, or T_P' }; numbers = [ pi exp(1) sqrt(2) (1+sqrt(5))/2 sqrt(3) sqrt(5) 299792458 6.02214129e23 9.80665 6.67384e-11 6.62606957e-34 8.3144621 8.9875517873681764e9 1.602176565e-19 5.2917721092e-11 9.10938291e-31 1.672621777e-27 1.660538921e-27 1.3806488e-23 96485.3365 5.670373e-8 101325 1.616199e-35 2.17651e-8 5.39106e-44 1.875545956e-18 1.416833e32 ]; holidayForFamousConstants(numbers,names)

On Jan 06, 0217 (1/6/0217), we can celebrate Elementary Charge, or e Day On Jun 01, 0217 (1/6/0217), we can celebrate Elementary Charge, or e Day On Jun 16, 0538 (16/6/0538), we can celebrate Atomic Mass Constant, or m_u Day On Aug 13, 0648 (13/8/0648), we can celebrate Boltzmann Constant, or k_B Day On Aug 09, 0665 (9/8/0665), we can celebrate Standard Gravity, or g Day On Sep 08, 0665 (9/8/0665), we can celebrate Standard Gravity, or g Day On Jan 09, 0938 (9/1/0938), we can celebrate Electron Mass, or m_e Day On Sep 01, 0938 (9/1/0938), we can celebrate Electron Mass, or m_e Day On Feb 05, 1013 (1013/2/5), we can celebrate Standard Atmosphere, or atm Day On May 02, 1013 (1013/2/5), we can celebrate Standard Atmosphere, or atm Day On Apr 06, 1380 (1380/6/4), we can celebrate Boltzmann Constant, or k_B Day On Jun 04, 1380 (1380/6/4), we can celebrate Boltzmann Constant, or k_B Day On Jan 02, 1414 (1414/2/1), we can celebrate Pythagoras' Constant, or Root 2 Day On Feb 01, 1414 (1414/2/1), we can celebrate Pythagoras' Constant, or Root 2 Day On Feb 13, 1414 (1414/2/13), we can celebrate Pythagoras' Constant, or Root 2 Day On Mar 21, 1414 (1414/21/3), we can celebrate Pythagoras' Constant, or Root 2 Day On Mar 08, 1416 (1416/8/3), we can celebrate Planck Temperature, or T_P Day On Aug 03, 1416 (1416/8/3), we can celebrate Planck Temperature, or T_P Day On Jan 04, 1421 (1/4/1421), we can celebrate Pythagoras' Constant, or Root 2 Day On Apr 01, 1421 (1/4/1421), we can celebrate Pythagoras' Constant, or Root 2 Day On Mar 08, 1446 (8/3/1446), we can celebrate Ideal Gas Constant, or R Day On Aug 03, 1446 (8/3/1446), we can celebrate Ideal Gas Constant, or R Day On Mar 14, 1592 (3/14/1592), we can celebrate Archimedes' Constant, or Pi Day On Jan 07, 1602 (1602/1/7), we can celebrate Elementary Charge, or e Day On Jun 17, 1602 (1602/17/6), we can celebrate Elementary Charge, or e Day On Jul 01, 1602 (1602/1/7), we can celebrate Elementary Charge, or e Day On Jan 09, 1616 (1616/1/9), we can celebrate Planck Length, or l_P Day On Sep 01, 1616 (1616/1/9), we can celebrate Planck Length, or l_P Day On Sep 19, 1616 (1616/19/9), we can celebrate Planck Length, or l_P Day On Mar 03, 1618 (1618/03/3), we can celebrate Golden Ratio, or Phi Day On Mar 03, 1618 (1618/03/3), we can celebrate Golden Ratio, or Phi Day On Jan 06, 1619 (1/6/1619), we can celebrate Planck Length, or l_P Day On Jun 01, 1619 (1/6/1619), we can celebrate Planck Length, or l_P Day On Mar 05, 1660 (1660/5/3), we can celebrate Atomic Mass Constant, or m_u Day On May 03, 1660 (1660/5/3), we can celebrate Atomic Mass Constant, or m_u Day On Feb 06, 1672 (1672/6/2), we can celebrate Proton Mass, or m_p Day On Jun 02, 1672 (1672/6/2), we can celebrate Proton Mass, or m_p Day On Jun 21, 1672 (1672/6/21), we can celebrate Proton Mass, or m_p Day On Jan 04, 1683 (1/4/1683), we can celebrate Planck Temperature, or T_P Day On Apr 01, 1683 (1/4/1683), we can celebrate Planck Temperature, or T_P Day On May 08, 1732 (1732/05/08), we can celebrate Root 3 Day On Aug 05, 1732 (1732/05/08), we can celebrate Root 3 Day On Feb 16, 1765 (16/02/1765), we can celebrate Elementary Charge, or e Day On May 29, 1772 (5/29/1772), we can celebrate Bohr Radius, or a_0 Day On Jan 06, 1803 (1/6/1803), we can celebrate Golden Ratio, or Phi Day On Jun 01, 1803 (1/6/1803), we can celebrate Golden Ratio, or Phi Day On Feb 07, 1828 (2/7/1828), we can celebrate Euler's Number, or e Day On Jul 02, 1828 (2/7/1828), we can celebrate Euler's Number, or e Day On Apr 05, 1875 (1875/5/4), we can celebrate Planck Charge, or q_P Day On May 04, 1875 (1875/5/4), we can celebrate Planck Charge, or q_P Day On Mar 14, 2015 (3/14/15), we can celebrate Archimedes' Constant, or Pi Day On Jan 02, 2016 (16/02/1), we can celebrate Elementary Charge, or e Day On Jan 04, 2016 (1/4/16), we can celebrate Planck Temperature, or T_P Day On Jan 06, 2016 (1/6/16), we can celebrate Planck Length, or l_P Day On Jan 06, 2016 (16/1/6), we can celebrate Planck Length, or l_P Day On Jan 08, 2016 (16/1/8), we can celebrate Golden Ratio, or Phi Day On Jan 16, 2016 (16/16/1), we can celebrate Planck Length, or l_P Day On Feb 01, 2016 (16/02/1), we can celebrate Elementary Charge, or e Day On Feb 07, 2016 (16/7/2), we can celebrate Proton Mass, or m_p Day On Feb 17, 2016 (16/02/17), we can celebrate Elementary Charge, or e Day On Mar 18, 2016 (16/18/03), we can celebrate Golden Ratio, or Phi Day On Apr 01, 2016 (1/4/16), we can celebrate Planck Temperature, or T_P Day On May 06, 2016 (16/6/05), we can celebrate Atomic Mass Constant, or m_u Day On Jun 01, 2016 (1/6/16), we can celebrate Planck Length, or l_P Day On Jun 01, 2016 (16/1/6), we can celebrate Planck Length, or l_P Day On Jun 05, 2016 (16/6/05), we can celebrate Atomic Mass Constant, or m_u Day On Jul 02, 2016 (16/7/2), we can celebrate Proton Mass, or m_p Day On Jul 26, 2016 (16/7/26), we can celebrate Proton Mass, or m_p Day On Aug 01, 2016 (16/1/8), we can celebrate Golden Ratio, or Phi Day On Feb 03, 2017 (17/3/2), we can celebrate Root 3 Day On Feb 16, 2017 (16/02/17), we can celebrate Elementary Charge, or e Day On Mar 02, 2017 (17/3/2), we can celebrate Root 3 Day On Mar 20, 2017 (17/3/20), we can celebrate Root 3 Day On May 29, 2017 (5/29/17), we can celebrate Bohr Radius, or a_0 Day On Jan 06, 2018 (1/6/18), we can celebrate Golden Ratio, or Phi Day On Feb 07, 2018 (2/7/18), we can celebrate Euler's Number, or e Day On May 07, 2018 (18/7/5), we can celebrate Planck Charge, or q_P Day On Jun 01, 2018 (1/6/18), we can celebrate Golden Ratio, or Phi Day On Jul 02, 2018 (2/7/18), we can celebrate Euler's Number, or e Day On Jul 05, 2018 (18/7/5), we can celebrate Planck Charge, or q_P Day On Mar 17, 2020 (17/3/20), we can celebrate Root 3 Day On Feb 06, 2021 (6/02/21), we can celebrate Avogadro's Number, or N_A Day On Jun 02, 2021 (6/02/21), we can celebrate Avogadro's Number, or N_A Day On Jun 07, 2021 (21/7/6), we can celebrate Planck Mass, or m_P Day On Jul 06, 2021 (21/7/6), we can celebrate Planck Mass, or m_P Day On Mar 06, 2022 (22/3/6), we can celebrate Root 5 Day On Jun 03, 2022 (22/3/6), we can celebrate Root 5 Day On Oct 13, 2025 (10/13/25), we can celebrate Standard Atmosphere, or atm Day On Jun 06, 2026 (6/6/26), we can celebrate Planck Constant, or h Day On Jun 06, 2026 (6/6/26), we can celebrate Planck Constant, or h Day On Jul 16, 2026 (16/7/26), we can celebrate Proton Mass, or m_p Day On Jan 08, 2027 (27/1/8), we can celebrate Euler's Number, or e Day On Feb 18, 2027 (27/18/2), we can celebrate Euler's Number, or e Day On Aug 01, 2027 (27/1/8), we can celebrate Euler's Number, or e Day On Jul 09, 2029 (29/9/7), we can celebrate Speed of Light, or c Day On Sep 07, 2029 (29/9/7), we can celebrate Speed of Light, or c Day On Jan 04, 2031 (31/4/1), we can celebrate Archimedes' Constant, or Pi Day On Apr 01, 2031 (31/4/1), we can celebrate Archimedes' Constant, or Pi Day On Apr 15, 2031 (31/4/15), we can celebrate Archimedes' Constant, or Pi Day On Jan 01, 2032 (1/01/32), we can celebrate Standard Atmosphere, or atm Day On Jan 01, 2032 (1/01/32), we can celebrate Standard Atmosphere, or atm Day On Jan 07, 2032 (1/7/32), we can celebrate Root 3 Day On Jan 10, 2032 (10/1/32), we can celebrate Standard Atmosphere, or atm Day On Jul 01, 2032 (1/7/32), we can celebrate Root 3 Day On Oct 01, 2032 (10/1/32), we can celebrate Standard Atmosphere, or atm Day On Feb 02, 2036 (2/2/36), we can celebrate Root 5 Day On Feb 02, 2036 (2/2/36), we can celebrate Root 5 Day On Jan 03, 2041 (3/1/41), we can celebrate Archimedes' Constant, or Pi Day On Mar 01, 2041 (3/1/41), we can celebrate Archimedes' Constant, or Pi Day On Jan 14, 2042 (14/1/42), we can celebrate Pythagoras' Constant, or Root 2 Day On Aug 31, 2044 (8/31/44), we can celebrate Ideal Gas Constant, or R Day On Jun 09, 2048 (9/6/48), we can celebrate Faraday Constant, or F Day On Sep 06, 2048 (9/6/48), we can celebrate Faraday Constant, or F Day On Mar 17, 2050 (17/3/2050), we can celebrate Root 3 Day On Jan 09, 2052 (52/9/1), we can celebrate Bohr Radius, or a_0 Day On Sep 01, 2052 (52/9/1), we can celebrate Bohr Radius, or a_0 Day On Sep 17, 2052 (52/9/17), we can celebrate Bohr Radius, or a_0 Day On Jan 09, 2053 (53/9/1), we can celebrate Planck Time, or t_P Day On Sep 01, 2053 (53/9/1), we can celebrate Planck Time, or t_P Day On Sep 10, 2053 (53/9/10), we can celebrate Planck Time, or t_P Day On Oct 09, 2053 (53/9/10), we can celebrate Planck Time, or t_P Day On Jul 18, 2055 (18/7/55), we can celebrate Planck Charge, or q_P Day On Mar 07, 2056 (56/7/03), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jul 03, 2056 (56/7/03), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jan 06, 2060 (1/6/60), we can celebrate Atomic Mass Constant, or m_u Day On Jan 22, 2060 (60/22/1), we can celebrate Avogadro's Number, or N_A Day On Feb 02, 2060 (60/2/2), we can celebrate Avogadro's Number, or N_A Day On Feb 02, 2060 (60/2/2), we can celebrate Avogadro's Number, or N_A Day On Feb 21, 2060 (60/2/21), we can celebrate Avogadro's Number, or N_A Day On Feb 23, 2060 (2/23/60), we can celebrate Root 5 Day On Mar 22, 2060 (22/3/60), we can celebrate Root 5 Day On Jun 01, 2060 (1/6/60), we can celebrate Atomic Mass Constant, or m_u Day On Jan 16, 2061 (16/1/61), we can celebrate Planck Length, or l_P Day On Feb 17, 2065 (2/17/65), we can celebrate Planck Mass, or m_P Day On Jul 21, 2065 (21/7/65), we can celebrate Planck Mass, or m_P Day On Feb 06, 2066 (66/2/6), we can celebrate Planck Constant, or h Day On Mar 07, 2066 (66/7/3), we can celebrate Gravitational Constant, or G Day On Jun 02, 2066 (66/2/6), we can celebrate Planck Constant, or h Day On Jun 26, 2066 (66/26/06), we can celebrate Planck Constant, or h Day On Jul 03, 2066 (66/7/3), we can celebrate Gravitational Constant, or G Day On Jan 14, 2068 (14/1/68), we can celebrate Planck Temperature, or T_P Day On May 06, 2070 (5/6/70), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jun 05, 2070 (5/6/70), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jan 06, 2072 (1/6/72), we can celebrate Proton Mass, or m_p Day On Jun 01, 2072 (1/6/72), we can celebrate Proton Mass, or m_p Day On Jun 06, 2073 (6/6/73), we can celebrate Gravitational Constant, or G Day On Jun 06, 2073 (6/6/73), we can celebrate Gravitational Constant, or G Day On Jan 08, 2075 (1/8/75), we can celebrate Planck Charge, or q_P Day On Aug 01, 2075 (1/8/75), we can celebrate Planck Charge, or q_P Day On Jan 02, 2076 (2/1/76), we can celebrate Planck Mass, or m_P Day On Feb 01, 2076 (2/1/76), we can celebrate Planck Mass, or m_P Day On Sep 29, 2079 (29/9/79), we can celebrate Speed of Light, or c Day On Jan 03, 2080 (1/3/80), we can celebrate Boltzmann Constant, or k_B Day On Jan 16, 2080 (16/1/80), we can celebrate Golden Ratio, or Phi Day On Mar 01, 2080 (1/3/80), we can celebrate Boltzmann Constant, or k_B Day On Jan 27, 2082 (27/1/82), we can celebrate Euler's Number, or e Day On Jan 04, 2083 (83/1/4), we can celebrate Ideal Gas Constant, or R Day On Apr 01, 2083 (83/1/4), we can celebrate Ideal Gas Constant, or R Day On Apr 14, 2083 (83/14/4), we can celebrate Ideal Gas Constant, or R Day On Aug 09, 2087 (8/9/87), we can celebrate Coulomb's Constant, or k_e Day On Sep 08, 2087 (8/9/87), we can celebrate Coulomb's Constant, or k_e Day On Jul 08, 2089 (89/8/7), we can celebrate Coulomb's Constant, or k_e Day On Aug 07, 2089 (89/8/7), we can celebrate Coulomb's Constant, or k_e Day On Feb 05, 2091 (5/2/91), we can celebrate Bohr Radius, or a_0 Day On Mar 05, 2091 (5/3/91), we can celebrate Planck Time, or t_P Day On Mar 09, 2091 (91/09/3), we can celebrate Electron Mass, or m_e Day On May 02, 2091 (5/2/91), we can celebrate Bohr Radius, or a_0 Day On May 03, 2091 (5/3/91), we can celebrate Planck Time, or t_P Day On Sep 03, 2091 (91/09/3), we can celebrate Electron Mass, or m_e Day On Sep 10, 2093 (9/10/93), we can celebrate Electron Mass, or m_e Day On Oct 09, 2093 (9/10/93), we can celebrate Electron Mass, or m_e Day On Apr 08, 2096 (96/4/8), we can celebrate Faraday Constant, or F Day On Aug 04, 2096 (96/4/8), we can celebrate Faraday Constant, or F Day On Feb 09, 2097 (2/9/97), we can celebrate Speed of Light, or c Day On Sep 02, 2097 (2/9/97), we can celebrate Speed of Light, or c Day On Jun 06, 2098 (98/06/6), we can celebrate Standard Gravity, or g Day On Jun 06, 2098 (98/06/6), we can celebrate Standard Gravity, or g Day On Jan 06, 2102 (1/6/02), we can celebrate Elementary Charge, or e Day On Jun 01, 2102 (1/6/02), we can celebrate Elementary Charge, or e Day On Jun 16, 2105 (16/6/05), we can celebrate Atomic Mass Constant, or m_u Day On Aug 09, 2106 (9/8/06), we can celebrate Standard Gravity, or g Day On Aug 13, 2106 (13/8/06), we can celebrate Boltzmann Constant, or k_B Day On Sep 08, 2106 (9/8/06), we can celebrate Standard Gravity, or g Day On Jan 09, 2109 (9/1/09), we can celebrate Electron Mass, or m_e Day On Sep 01, 2109 (9/1/09), we can celebrate Electron Mass, or m_e Day On Jan 03, 2110 (10/1/3), we can celebrate Standard Atmosphere, or atm Day On Feb 13, 2110 (10/13/2), we can celebrate Standard Atmosphere, or atm Day On Mar 01, 2110 (10/1/3), we can celebrate Standard Atmosphere, or atm Day On Jun 08, 2113 (13/8/06), we can celebrate Boltzmann Constant, or k_B Day On Aug 06, 2113 (13/8/06), we can celebrate Boltzmann Constant, or k_B Day On Jan 04, 2114 (1/4/14), we can celebrate Pythagoras' Constant, or Root 2 Day On Jan 04, 2114 (14/1/4), we can celebrate Pythagoras' Constant, or Root 2 Day On Jan 06, 2114 (14/1/6), we can celebrate Planck Temperature, or T_P Day On Feb 14, 2114 (14/14/2), we can celebrate Pythagoras' Constant, or Root 2 Day On Mar 08, 2114 (8/3/14), we can celebrate Ideal Gas Constant, or R Day On Apr 01, 2114 (1/4/14), we can celebrate Pythagoras' Constant, or Root 2 Day On Apr 01, 2114 (14/1/4), we can celebrate Pythagoras' Constant, or Root 2 Day On Jun 01, 2114 (14/1/6), we can celebrate Planck Temperature, or T_P Day On Aug 03, 2114 (8/3/14), we can celebrate Ideal Gas Constant, or R Day On Aug 16, 2114 (14/16/8), we can celebrate Planck Temperature, or T_P Day On Feb 06, 2141 (6/02/2141), we can celebrate Avogadro's Number, or N_A Day On Jun 02, 2141 (6/02/2141), we can celebrate Avogadro's Number, or N_A Day On Jan 05, 2176 (2176/5/1), we can celebrate Planck Mass, or m_P Day On May 01, 2176 (2176/5/1), we can celebrate Planck Mass, or m_P Day On May 10, 2176 (2176/5/10), we can celebrate Planck Mass, or m_P Day On Oct 05, 2176 (2176/5/10), we can celebrate Planck Mass, or m_P Day On Jun 07, 2236 (2236/06/7), we can celebrate Root 5 Day On Jul 06, 2236 (2236/06/7), we can celebrate Root 5 Day On Oct 13, 2500 (10/13/2500), we can celebrate Standard Atmosphere, or atm Day On Jun 06, 2606 (6/6/2606), we can celebrate Planck Constant, or h Day On Jun 06, 2606 (6/6/2606), we can celebrate Planck Constant, or h Day On Jul 16, 2621 (16/7/2621), we can celebrate Proton Mass, or m_p Day On Jan 28, 2718 (2718/28/1), we can celebrate Euler's Number, or e Day On Feb 08, 2718 (2718/2/8), we can celebrate Euler's Number, or e Day On Aug 02, 2718 (2718/2/8), we can celebrate Euler's Number, or e Day On Feb 09, 2997 (2997/9/2), we can celebrate Speed of Light, or c Day On Sep 02, 2997 (2997/9/2), we can celebrate Speed of Light, or c Day On Sep 24, 2997 (2997/9/24), we can celebrate Speed of Light, or c Day On May 09, 3141 (3141/5/9), we can celebrate Archimedes' Constant, or Pi Day On Sep 05, 3141 (3141/5/9), we can celebrate Archimedes' Constant, or Pi Day On Jan 07, 3205 (1/7/3205), we can celebrate Root 3 Day On Jul 01, 3205 (1/7/3205), we can celebrate Root 3 Day On Jan 01, 3250 (1/01/3250), we can celebrate Standard Atmosphere, or atm Day On Jan 01, 3250 (1/01/3250), we can celebrate Standard Atmosphere, or atm Day On Jan 10, 3250 (10/1/3250), we can celebrate Standard Atmosphere, or atm Day On Oct 01, 3250 (10/1/3250), we can celebrate Standard Atmosphere, or atm Day On Feb 02, 3606 (2/2/3606), we can celebrate Root 5 Day On Feb 02, 3606 (2/2/3606), we can celebrate Root 5 Day On Jan 03, 4159 (3/1/4159), we can celebrate Archimedes' Constant, or Pi Day On Mar 01, 4159 (3/1/4159), we can celebrate Archimedes' Constant, or Pi Day On Jan 14, 4213 (14/1/4213), we can celebrate Pythagoras' Constant, or Root 2 Day On Aug 31, 4462 (8/31/4462), we can celebrate Ideal Gas Constant, or R Day On Jun 09, 4853 (9/6/4853), we can celebrate Faraday Constant, or F Day On Sep 06, 4853 (9/6/4853), we can celebrate Faraday Constant, or F Day On Jul 07, 5291 (5291/7/7), we can celebrate Bohr Radius, or a_0 Day On Jul 07, 5291 (5291/7/7), we can celebrate Bohr Radius, or a_0 Day On Jul 18, 5545 (18/7/5545), we can celebrate Planck Charge, or q_P Day On Mar 07, 5670 (5670/3/7), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jul 03, 5670 (5670/3/7), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jan 04, 6022 (6022/1/4), we can celebrate Avogadro's Number, or N_A Day On Jan 14, 6022 (6022/14/1), we can celebrate Avogadro's Number, or N_A Day On Apr 01, 6022 (6022/1/4), we can celebrate Avogadro's Number, or N_A Day On Dec 14, 6022 (6022/14/12), we can celebrate Avogadro's Number, or N_A Day On Jan 06, 6053 (1/6/6053), we can celebrate Atomic Mass Constant, or m_u Day On Jun 01, 6053 (1/6/6053), we can celebrate Atomic Mass Constant, or m_u Day On Feb 23, 6067 (2/23/6067), we can celebrate Root 5 Day On Mar 22, 6067 (22/3/6067), we can celebrate Root 5 Day On Jan 16, 6199 (16/1/6199), we can celebrate Planck Length, or l_P Day On Feb 17, 6510 (2/17/6510), we can celebrate Planck Mass, or m_P Day On Jul 21, 6510 (21/7/6510), we can celebrate Planck Mass, or m_P Day On Jun 09, 6626 (6626/06/9), we can celebrate Planck Constant, or h Day On Sep 06, 6626 (6626/06/9), we can celebrate Planck Constant, or h Day On Apr 08, 6673 (6673/8/4), we can celebrate Gravitational Constant, or G Day On Aug 04, 6673 (6673/8/4), we can celebrate Gravitational Constant, or G Day On Jan 14, 6833 (14/1/6833), we can celebrate Planck Temperature, or T_P Day On May 06, 7037 (5/6/7037), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jun 05, 7037 (5/6/7037), we can celebrate Stefan-Boltzmann Constant, or Theta Day On Jan 06, 7262 (1/6/7262), we can celebrate Proton Mass, or m_p Day On Jun 01, 7262 (1/6/7262), we can celebrate Proton Mass, or m_p Day On Jun 06, 7384 (6/6/7384), we can celebrate Gravitational Constant, or G Day On Jun 06, 7384 (6/6/7384), we can celebrate Gravitational Constant, or G Day On Jan 08, 7554 (1/8/7554), we can celebrate Planck Charge, or q_P Day On Aug 01, 7554 (1/8/7554), we can celebrate Planck Charge, or q_P Day On Jan 02, 7651 (2/1/7651), we can celebrate Planck Mass, or m_P Day On Feb 01, 7651 (2/1/7651), we can celebrate Planck Mass, or m_P Day On Sep 29, 7924 (29/9/7924), we can celebrate Speed of Light, or c Day On Jan 16, 8033 (16/1/8033), we can celebrate Golden Ratio, or Phi Day On Jan 03, 8064 (1/3/8064), we can celebrate Boltzmann Constant, or k_B Day On Mar 01, 8064 (1/3/8064), we can celebrate Boltzmann Constant, or k_B Day On Jan 27, 8281 (27/1/8281), we can celebrate Euler's Number, or e Day On Apr 06, 8314 (8314/4/6), we can celebrate Ideal Gas Constant, or R Day On Jun 04, 8314 (8314/4/6), we can celebrate Ideal Gas Constant, or R Day On Aug 09, 8755 (8/9/8755), we can celebrate Coulomb's Constant, or k_e Day On Sep 08, 8755 (8/9/8755), we can celebrate Coulomb's Constant, or k_e Day On May 05, 8987 (8987/5/5), we can celebrate Coulomb's Constant, or k_e Day On May 05, 8987 (8987/5/5), we can celebrate Coulomb's Constant, or k_e Day On Mar 05, 9106 (5/3/9106), we can celebrate Planck Time, or t_P Day On May 03, 9106 (5/3/9106), we can celebrate Planck Time, or t_P Day On Mar 08, 9109 (9109/3/8), we can celebrate Electron Mass, or m_e Day On Aug 03, 9109 (9109/3/8), we can celebrate Electron Mass, or m_e Day On Feb 05, 9177 (5/2/9177), we can celebrate Bohr Radius, or a_0 Day On May 02, 9177 (5/2/9177), we can celebrate Bohr Radius, or a_0 Day On Sep 10, 9382 (9/10/9382), we can celebrate Electron Mass, or m_e Day On Oct 09, 9382 (9/10/9382), we can celebrate Electron Mass, or m_e Day On Mar 05, 9648 (9648/5/3), we can celebrate Faraday Constant, or F Day On May 03, 9648 (9648/5/3), we can celebrate Faraday Constant, or F Day On Feb 09, 9792 (2/9/9792), we can celebrate Speed of Light, or c Day On Sep 02, 9792 (2/9/9792), we can celebrate Speed of Light, or c Day On May 06, 9806 (9806/6/5), we can celebrate Standard Gravity, or g Day On Jun 05, 9806 (9806/6/5), we can celebrate Standard Gravity, or g Day

#### Now it's your turn

What other special numbers would you like to hold holidays for? Measurements of the Earth? Unit conversion factors? Interplanetary distances? The Fibonacci sequence? Try my function with some of your favorites and post them in the comments.

**Category:**- Data types,
- Fun

## Comments

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