Question

Square root of 400 is:

• A. 40
• B. 25
• C. 20
• D. 100

Hint:

Knowing perfect squares up to at least 30 × 30 helps in quickly finding square roots without calculation.

Answer 1

The Correct Option is C

The square root of a number is a value that, when multiplied by itself, gives the original number. To find the square root of 400, we need to find a number which, when multiplied by itself, results in 400.

Let's denote the square root of 400 as \( x \). This gives us the equation:

\( x^2 = 400 \)

To find \( x \), we take the square root of both sides:

\( x = \sqrt{400} \)

We need to determine which number multiplied by itself equals 400. Testing the possible options:

20	\( 20 \times 20 = 400 \)
25	\( 25 \times 25 = 625 \)
40	\( 40 \times 40 = 1600 \)
100	\( 100 \times 100 = 10000 \)

From the calculations above, \( 20 \times 20 = 400 \), confirming that:

The square root of 400 is 20.