Methods of computing square roots Facts for Kids

A square root is a special number that, when multiplied by itself, gives you another number. Finding a square root is the opposite of squaring a number. For example, the square root of 9 is 3, because 3 multiplied by 3 equals 9.

Sometimes, a number can have two square roots! For instance, the square root of 4 can be 2, because 2 multiplied by 2 is 4. But it can also be -2, because -2 multiplied by -2 also equals 4. Usually, when people talk about "the" square root, they mean the positive one.

Many square roots are irrational numbers. This means they are numbers that go on forever after the decimal point without repeating. You can't write them down perfectly as a simple fraction or a short decimal. For example, the square root of 28 is about 5.291502622... It keeps going! So, you often need to decide how accurate you need your answer to be.

Some numbers, like negative numbers, don't have a "normal" square root that you can find on a number line. For example, you can't multiply a number by itself to get -4, because 2 times 2 is 4, and -2 times -2 is also 4. These kinds of square roots involve something called complex numbers, which you might learn about in more advanced math.

Using a Calculator

Most calculators have a special button to help you find square roots quickly. It usually looks like this: $\sqrt{}$ .

General Steps	Example
First, clear your calculator screen. Press the C button a few times. Next, type in the number you want to find the square root of. Then, press the square root button ( $\sqrt{}$ ). The number that appears on the screen is your answer! Remember, there might be a positive and a negative answer, but the calculator usually shows the positive one.	Press the C button a few times. Type in 16. Press the $\sqrt{}$ button. The answer you see will be 4. Keep in mind that -4 is also a correct square root for 16!

Estimating Square Roots

Sometimes you don't need a super precise answer, or you don't have a calculator. You can estimate a square root by finding numbers that are close.

How to Estimate	Example
Suppose you want to find the square root of a number, let's call it $N$ . Think of a number, let's call it $A$ , that when you multiply it by itself ( $A^2$ ), it's close to $N$ . If $A^2$ is close to $N$ , then $A$ is a good guess for the square root of $N$ .	Let's try to estimate the square root of 2. We know that 1 multiplied by 1 (Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): 1^2 ) is 1. We also know that 2 multiplied by 2 ( $2^2$ ) is 4. Since 2 is between 1 and 4, the square root of 2 must be a number between 1 and 2. This tells us that the square root of 2 is about 1.414...

Methods of computing square roots facts for kids

Using a Calculator

Estimating Square Roots

See also