What number multiplied by itself equals 400?

Here we will answer: What number multiplied by itself gives 400? In other words, what number times itself will equal 400?

We have identified many different ways of getting the answer to this question:

Algebra Method:
Make an algebra equation and solve for x:

x • x = 400
x = 20

Square Root Method:
Take the square root of 400 to get the answer:

√400 = 20

Exponent Method:
Make the base 400 and the exponent 0.5 to get the answer:

400^0.5 = 20

There you go! Now you know how to calculate "What number multiplied by itself equals 400?"

The bottom line is that 20 times itself equals 400 as illustrated here:

20 x 20 = 400

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The answer on this page is rounded to the nearest thousandth, if necessary.