Question

Enter the value of 65².

• A. 4225

Answer 1

The correct option is A 4225
A number of the form $a5$ when squared gives 100a(a + 1) + 25.

This can easily be done by writing the product of $a$ and $a+1$ and attaching 25 to it on it's right side.

In 65², $a$ is 6.
a(a+1) = 6(6+1)
= 6(7)
= 42

So, 65² = 4225

or 65² = 100(42) + 25 = 4225