Here are some resources that I use a lot that might be useful to you:

**https://projecteuler.net/archives
**

Project Euler is a collection of programming challenges. However, many of them can be solved with math instead of programming. They're fun either way.

**https://fivethirtyeight.com/tag/the-riddler/
**

A weekly puzzle series, where each puzzle is meant to be solved using some form of math. Most of the math isn't too challenging, but rather tricky.

**https://www.quantamagazine.org/tag/insights-puzzle/
**

Quanta is a great publication that puts out science/math articles. It also has a pretty good puzzle series.

**http://puzzlor.com
**

These puzzles are meant to be solved using operations research techniques, but calculus, probability, and other approaches can also be used.

Posted November 14th
by EN