Lucky friday the thirteenth

Number Theory Level 2

Being born on the thirteenth of the month, Calvin considers the 13th to be a lucky day. What is the most number of Friday the 13th's that can occur in a calendar year?

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Lucky friday the thirteenth

Excel in math and science

Master concepts by solving fun, challenging problems.

It's hard to learn from lectures and videos

Learn more effectively through short, interactive explorations.

Used and loved by over 6 million people

Learn from a vibrant community of students and enthusiasts, including olympiad champions, researchers, and professionals.

Learn from a vibrant community of students and enthusiasts,
including olympiad champions, researchers, and professionals.

Learn from a vibrant community of students and enthusiasts,
including olympiad champions, researchers, and professionals.