CCSS: 6.EE.A.2.C, 7.EE.B.3, MP1, MP6

TEKS: 6.3D, 6.7D, 7.3A, 7.3B

Friday the 13th

Andrzej Tokarski/Alamy Stock Photo (calendar); (cat)

This year, the spookiest month also has the spookiest day: Friday the 13th! Every year has at least one of these doomed days, but they occur in October every 11 years or so. Considering Friday unlucky dates back to medieval times, and the number 13 was considered unlucky in ancient Norse and Christian traditions. The two superstitions morphed into Friday the 13th in the 1800s. By the 1900s, fear of Friday the 13th was well established. Even former President Franklin D. Roosevelt believed Friday the 13th was unlucky!

Read on to learn more about the spookiest day of the year! Then plug in the numbers to solve the equation below and reveal a final fact.


Maximum number of Friday the 13ths that can happen in a calendar year


Solent News/Shutterstock

 Films in the Friday the 13th horror series, which features Jason Voorhees in his signature hockey mask


Octavio Jones/TAS23/Getty Images for for TAS Rights Management

Number of times Taylor Swift’s birthday—December 13—has been on a Friday. She considers 13 her lucky number!


Approximate number of Americans with fear of Friday the 13th, which is known as