Introducing Fractional Birthdays 🍰 🎉

Another one to add to the Recreational Mathematics list

Dr Who — Recreational Mathematics

The concept behind this one is relatively straightforward.

1. Take the month of the year and divide that by the day, or vice versa depending on whichever number is smaller. The point is that you want a number lower than 1. For instance, if your birthday is May 25th: The month of the birthday is May i.e. 5 and the day of the year is 25, it would be 5/25 = 0.2.
2. Now you take that number and times it by 365. E.g. 365 * 0.2 = 73. 73rd day of the year is March 14th.

So, for someone with a birthday of May 25th, your fractional birthday is March 14!

Wrapping it all up

1. Day of Birthday (e.g. 25)
2. The month of Birthday (e.g. 5 which is May)
3. Take the smaller number and divide by larger number (e.g. 5/25 = 0.2)
4. Multiply the number by days in a year (e.g. 0.2 * 365 = 73 which is March 14th)