# Pi Day and doomsdays

Today is **Pi Day!**

**Pi (π) **is the ratio of the circumference of a circle to its diameter. It is an irrational number but often, its decimal approximation of 3.14 is used. Since 1988, 3/14 or March 24 is celebrated as **Pi Day**. In November 2019, UNESCO’s 40^{th }General Conference designated **Pi Day** as the **International Day of Mathematics.**

While various activities are held by Math enthusiasts in schools, colleges, and universities world-wide to commemorate this day, we are also reminded that **Pi Day **is also a **Doomsday**. Doomsdays are easy to remember dates which fall on a certain day each year.

Since **Pi Day** **2024** falls on a Thursday, we can identify the Thursdays in every month.

For even-numbered months, the following are Thursdays:

April 4 (4/4)

June 6 (6/6)

August 8 (8/8)

October 10 (10/10)

December (12/12)

Adding or subtracting multiples of 7 to these dates will give you the other Thursdays in that month. For example, this year, October 3, 17, 24 and 31 are Thursdays. Also, December 26 is a Thursday, so Christmas Day is a Wednesday.

These dates also fall on Thursdays this year:

May 9 (5/9)

July 11 (7/11)

September 5 (9/5)

November 7 (11/7)

So, for the odd-numbered months, we just have to imagine a friend working at **7-11 **from **9 AM **to** 5 PM**.

We also know that the last day of February was a Thursday. Since 2024 is a leap year, February 1 was also a Thursday and so was January 4.