Martin Gardner was a puzzle enthusiast, a magician, and a lifelong believer in and champion of the power and beauty of mathematics
Take a right angled triangle whose two shorter sides are 6cm long and 8cm long. Draw squares on each of those sides. Add their areas—36 and 64 sq cm, respectively. What you get is, as Pythagoras told us a long time ago, the area of the square on the longest side, 100 sq cm.