Showing what's behind the curtain

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 in a 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

Answers and techniques for solving the Impossible Test Christmas. Revised for newest version 1/17/2013

Comparing four-sided and six-sided dice

Skew-cost coding

Odd triplets in Pascal’s triangle.