# What is the square root of 20 times the square root of 80?

Sep 12, 2015

40.

#### Explanation:

When multiplying square roots it's important to know that you can do it in almost the same way as with regular numbers.

$\sqrt{a} \cdot \sqrt{b} = \sqrt{a \cdot b}$

Therefore,

$\sqrt{20} \cdot \sqrt{80} = \sqrt{20 \cdot 80} = \sqrt{1600} = 40$