When measuring things, a whole number might not be the best answer. A distance might be longer than 5 meters, but less than 6 meters. Meter sticks are marked off in parts of a meter. Decimals are formed by marking off a ruler in ten equal parts. Each part is a tenth. 5.2 meters is a little bit longer than 5 meters. 5.7 meters is a little bit shorter than 6 meters. Each of these tenths can be marked with ten smaller parts. The one hundred centimeters on a meter stick are done this way; by marking ten equal parts, then marking ten equal parts of each of those parts.