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Square Root Calculator

Enter a number to get its square root as a decimal and, where possible, the simplified radical form. The factoring steps are shown below the result.

Chris Terry
By Chris Terry, Editor
Updated June 20, 2026

Enter a number

Try a perfect square like 144, or a number with a square factor like 72.

Result

Square root--
Decimal--
Simplified radical--
Enter a number to see the steps.

How to find a square root

The square root of a number n is the value that, multiplied by itself, equals n. The radical symbol is the check-mark sign placed over the number.

sqrt(n) = x, where x times x = n

When n is a perfect square the root is a whole number: sqrt(144) = 12 because 12 x 12 = 144. When n is not a perfect square, the root is irrational, so the calculator returns a decimal rounded to several places and, when a perfect-square factor exists, the simplified radical form.

Worked example: sqrt(72)

72 is not a perfect square, but it has a perfect-square factor. Break it down step by step.

Step 1. Find the largest perfect-square factor of 72. Since 72 = 36 x 2 and 36 is a perfect square, use 36.
Step 2. Split the radical: sqrt(72) = sqrt(36 x 2) = sqrt(36) x sqrt(2).
Step 3. Take the root of the perfect square: sqrt(36) = 6, so sqrt(72) = 6 sqrt(2).
Step 4. As a decimal, 6 sqrt(2) is about 8.485.

For background on radicals and irrational roots, see Wolfram MathWorld on the square root.

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Good to know

Frequently asked questions

How do you calculate a square root by hand?

Find a number that multiplies by itself to give your value. For perfect squares like 144 the answer is exact (12). For others, estimate between the two nearest perfect squares, then refine.

What is a simplified radical form?

It pulls the largest perfect-square factor out of the radical. For example sqrt(72) = sqrt(36 x 2) = 6 sqrt(2).

Can you take the square root of a negative number?

Not within the real numbers. The square root of a negative number is imaginary, written with i, such as sqrt(-9) = 3i.

Is the square root of a decimal allowed?

Yes. This tool accepts decimals and returns the decimal root rounded to several places.

Chris Terry
About the author
Chris Terry
Editor, Encore Editorial

Editor at Encore Editorial, Chris Terry sets the editorial standards here and turns dense topics into plain English. He has written widely on education, finance, and consumer markets.