One 18-inch pizza contains more pizza than two 12-inch pizzas - about 12.5% more. (Area: 18" = π·9² = 81π; two 12" = 2×(π·6²) = 72π.)

American, Russian, and other military forces around the world train and use sea animals such as dolphins, walruses, and whales for surveillance and various other purposes.

It is estimated that up to 12% of women might be tetrachromats - capable of perceiving millions more colours than the average person. Men generally cannot have this condition.

Rock-paper-scissors originates from Jan-ken, a Japanese variation of a Chinese game brought to Japan in the 17th century, which featured a slug, frog, and snake.

Research shows that consumer demand for sausages is inversely proportional to the health of the economy.

Blinking throughout the day adds up to having your eyes closed for about 30 minutes.

Spain, Mexico, Argentina, and many other countries don't have a tooth fairy; they have a tooth rat named El Ratoncito Pérez.