Advertisement

### Question

What is 139 × 25?

**A**

3475.

**B**

3480.

**C**

3470.

**D**

3485.

**Soln.**

**Ans: a**

This is a multiplication by a power of 5. The best way is to observe that 25 = 5^{2}. There are 2 powers of 5. So append 2 zeroes and divide by 2^{2}, like this: $13900/4$ = 3475.