# What is the square root of 20 times the square root of 5?

Sep 12, 2015

10.

#### Explanation:

The rule for multiplying square roots is that $\sqrt{a} \cdot \sqrt{b} = \sqrt{a b}$
It's important to clarify that because it can be confusing if you don't understand that radical multiplication is just like normal multiplication. Anyway, all we have to do now is apply this property:

$\sqrt{20} \cdot \sqrt{5} = \sqrt{20 \cdot 5} = \sqrt{100} = 10$