Chapter 4, Problem 1CST

To determine

To determine which number is not prime

Answer to Problem 1CST

D-57

Explanation of Solution

Given information:

Numbers 7, 37,53 & 57

Calculation:

A number is prime if it divisible by only two numbers 1 & itself.

Let us check each options one by one.

A. 7

So the prime factors of 7 are $7=7\times 1$

Hence, 7 is prime.

B. 37

So the prime factors of 7 are $37=37\times 1$

Hence, 37 is prime.

C. 53

So the prime factors of 53 are $53=53\times 1$

Hence, 53 is prime.

D. 57

So the prime factors of 57 are $57=19\times 3\times 1$

Since the prime factors for 57 are 1,3,19 and 57. So, 57 is not prime,

Conclusion-

D-57