As people around the world take more and more walks around their neighborhood, in order to stay sane during sheltering in place orders, a growing number of math teachers and amateur mathematicians are turning them into math walks. Sidewalk math is where you chalk out a math riddle on the sidewalk. Passersby see the math on their walks and then try to solve it there and then, or take a photo and use it as their scratchpad when back in their homes.

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