In mathematics, a remainder is what's left over after you divide one number by another and can't divide evenly. When you divide 17 cookies among 5 friends, each friend gets 3 cookies, with 2 left over: those 2 cookies are the remainder.

Remainders show up constantly in everyday life. If 23 students need to form teams of 4, you can make 5 complete teams with 3 students remaining. Those 3 students are the remainder, and you'll need to figure out what to do with them.

The word also means what's left after you've taken something away or used most of it. After a big party, the remainder of the cake sits in the refrigerator. After you've spent most of your allowance, the remainder stays in your piggy bank. A bookstore might sell its remainders at a discount: these are the leftover books after most copies have sold.

Understanding remainders helps you solve real problems: How many cars do we need if 31 people are going on a field trip and each car holds 5? You'd need 7 cars, because after filling 6 cars completely, there's a remainder of 1 person who still needs a ride.