What is a square root?

The square root of a number is the value that, multiplied by itself, gives that number. The square root of 25 is 5, because 5 times 5 is 25. Most numbers do not have a whole square root, so the result is a decimal.

Can you take the square root of a negative number?

Not within the real numbers, because no real number multiplied by itself gives a negative result. The square root of a negative number is an imaginary number, which is beyond this calculator. Enter a number of zero or more.

What is a perfect square?

A perfect square is a whole number whose square root is also a whole number, such as 4, 9, 16, and 25. Their roots are 2, 3, 4, and 5. Numbers in between have square roots that are decimals.

Square Root Calculator

Find the square root of any number. Type a number and the calculator shows its square root straight away, along with its square and cube root. The square root is the value that multiplied by itself gives your number.

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Number

square root

Square (n²)0

Cube root0

How it works

The square root reverses squaring. If you square the answer, you get back your number. The calculator also shows the square, which is the number times itself, and the cube root, the value that cubed gives your number.

Worked example

The square root of 50 is about 7.071, because 7.071 times 7.071 is roughly 50. The square of 50 is 2,500, and the cube root of 50 is about 3.684.

Related calculators

Exponent Calculator: powers of a number.
Scientific Calculator: advanced functions.
Pythagorean Theorem Calculator: uses square roots.
Standard Calculator: everyday arithmetic.

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