Question

What is the square root of 64?

• A. 2
• B. 3
• C. 5
• D. 6

Answer 1

The correct option is C

5

We know that sum of consecutive odd numbers gives a square number. So, if we keep subtracting consecutive odd numbers from the given square number, we will eventually get 0. The number of steps taken to get 0 is equal to the square root of the given number.

Step 1 $\Rightarrow$ 64 - 1 = 63

Step 2 $\Rightarrow$ 63 - 3 = 60

Step 3 $\Rightarrow$ 60 - 5 = 55

Step 4 $\Rightarrow$ 55 - 7 = 48

Step 5 $\Rightarrow$ 48 - 9 = 39

Step 6 $\Rightarrow$ 39 - 11 = 28

Step 7 $\Rightarrow$ 28 - 13 = 15

Step 8 $\Rightarrow$ 15 - 15 = 0

It took 8 steps.
So, square root of 64 is 8.

Caution: This method is not advised for larger numbers.