Calculate the square root of 81 times 16.
Almost immediately, I recognise that both 81 and 16 are perfect squares. 81 equals nine squared and 16 equals four squared. When two numbers are raised to the same power, we can multiply their bases. The nine and the four are both raised to the second power, which means we can multiply the base, nine times four, and then raise that to the second power. Nine times four equals 36. So we’re left with 36 squared. Here, the square root cancels out the square leaving us with 36.
The square root of 81 times 16 equals 36.