A hundredth is one part when something is divided into one hundred equal pieces. If you slice a pizza into 100 tiny, equal slices (which would be quite a feat!), each slice would be one hundredth of the pizza. In decimal form, one hundredth is written as 0.01.

The word becomes especially important when you work with money. A penny is one hundredth of a dollar, which is why we write $0.01 for one cent. When something costs $3.47, that means 3 dollars plus 47 hundredths of a dollar (or 47 pennies).

In measurement, hundredths matter for precision. A swimmer might win a race by three hundredths of a second: 0.03 seconds. That's an almost invisible sliver of time, but it's enough to determine who gets the gold medal. Scientists measuring chemicals, engineers designing bridges, and anyone who needs exact measurements often work with hundredths.

When you see the word used as an adjective, like “the hundredth day of school,” it means the number 100 in a sequence: the 100th item in order. Your hundredth book would be the one you finish after reading 99 others. The hundredth customer at a store opening might win a prize simply for being number 100 in line.