FRIDAY 13

BY NIKKI BACON

PROBLEM: FRIDAY 13

1. PROVE that there is at least one Friday the 13th in some month during each year.

2. PROVE that there is at most three Friday the 13ths any given year.

To prove that there is at least one Friday the 13th and at most 3 Friday the 13ths in any given year I used a spread sheet in excel. I set up a spread sheet to look at when and how many Friday the 13ths there were in a year when January 1st is either a Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, or Saturday. To see this spread sheet, click here. I did this for a leap year and a non leap year. By doing this, I exhausted all the possible Friday the 13ths in any given year.

I then went through the spread sheet and highlighted all the Friday the 13ths in every possible year. After highlighting, I organized my findings using excel. I found that there is at least one Friday the 13th in some month during each year and at most 3 Friday the 13ths in any given year. To see this, click here.

3. Joe Hooten, Professor Emeritus at the University of Georgia, observed in 1998 both February and March have a Friday the 13th. That is, there is a Friday the 13th in two consecutive months.

In what year will this occur again?

Is there a cycle that can be specified for determining the years in which there will be two consecutive months with Friday the 13th?