Showing what's behind the curtain

Right triangles with integer coordinates

Finding Nim positions consisting of heap sizes n, 2n and 3n for n ≤ 2^{30} that result in a losing game.

Su Doku

Cube digit pairs

Make plurals of English words from the given input

Build a fence to maximize an area enclosed between the fence and a fixed wall

Add two reversed numbers and output their reversed sum

Find the number of trailing zeros for any factorial

Find the largest volume of a cylinder cut and formed from a sheet of paper

How many 8 × 8 chess boards are embedded in a painting which consists solely of black and white squares, arranged in a checkered pattern