Mark Girard’s Solutions to the 538 Riddlers

I really like puzzles! The puzzles from the Riddler give me a chance to explore something new each week.

Here is a description of The Riddler from the FiveThirtyEight website:

Welcome to The Riddler. Every week, I offer up problems related to the things we hold dear around here: math, logic, and probability.

This is a collection of all of my solutions to the weekly puzzles from FiveThirtyEight’s The Riddler series.


Date (link to puzzle)DescriptionMy solutionRelevant code
April 23Random votinglink 
April 16Lunar phase speedlink 
April 9One-way outlinkcode
April 2Outthink the Sphinxlink 
March 26March Mathnesslink 
March 19Square residues mod 10link 
March 12The biggest pielink 
March 5Baseball numerologylink 
February 19Random Jengalink 

Older Solutions

Some solutions to older puzzles can be found at my old website here.