# Q. Which number amongst 2^40, 3^21, 4^18 and 8^12 is the smallest?

a. 2^40

b. 3^21

c. 4^18

d. 8^12

Correct Answer: b. 3^21

#### Question from UPSC Prelims 2022 CSAT Paper

**Explanation : **

## Which number among is smallest:

2^40, 3^21, 4^18, and 8^12

We can also write them as: 2^40, 3^21, 2^36, and 2^36.

We can rewrite 2^36 and 3^21 as:

2^12 and 3^7

4096 > 2187

Hence, **3^21 is the smallest number**.