Square Roots

A square root is a special kind of math idea. It is the opposite of squaring a number. When you multiply a number by itself, you get a square. The square root tells you which number was used to make that square.

How Square Roots Work

The square root of 9 is 3 because 3 times 3 equals 9. The square root of 16 is 4 because 4 times 4 equals 16. We use a special symbol that looks like a check mark to show a square root. Some numbers have easy square roots, and some do not. Numbers with whole number square roots are called perfect squares.

Where We Use Them

Square roots help us find the side of a square when we know its area. Builders use them when making floors and walls. Scientists use them in many kinds of math. They also help with a famous rule about triangles called the Pythagorean theorem. Square roots show up in lots of real life problems.

Fun Facts

• The square root symbol is called a radical sign.
• The square root of 100 is 10.
• Zero is the only number whose square root is itself.

Did You Know?

Ancient people from Babylon knew about square roots more than 3,000 years ago. They wrote them on clay tablets.