Many real-life math problems don't require exact solutions or precise calculations. When you need an approximate idea of length, you have a handy-dandy "ruler" always nearby: your body. Yes, your body — and its various parts — can serve as a quick length estimator.

  • Your hand: The width of your palm is about 4 inches (10 centimeters).

  • Your foot: An average foot is about 12 inches long.

  • Your forearm from elbow to fingertip: Your forearm is about 1.5 feet (46 centimeters).

  • From nose to finger tip: The distance between your nose and your fingertip when your arm is extended is about a yard (36 inches). If you haven't used this method yourself, ask your mother or grandmother: It's the traditional way of measuring cloth.

  • The distance of one full stride: Called a pace, it's about 58 inches, just short of 6 feet. The Romans used this measurement, and so can you!

These estimates are just that: estimates. A more accurate way use your body parts to estimate length is to know your own measurements: the width of your own palm, the length of your own foot, and so on. Then, wherever you are, you'll have a pretty accurate ruler very close by.