Question

8. Which of the following is a prime number?
(a) 143
(b) 131
(c) 147
(d) 161​

Answer 1

(b) 131

131 is a prime number.

Given data:

Four numbers 143, 131, 147 and 161

To find:

The prime number from the given four numbers

Concept:

If a number greater than 1 has only two factors, 1 and itself, the number is a prime number.

For example, 2. It has two factors, 1 and 2 (itself).

Step-by-step explanation:

We factorize the given numbers and see which number has only two factors needed to be a prime number.

(a) 143

We have 143 = 11 × 13

So, 143 is not a prime number.

(b) 131

We have 131 = 1 × 131

So, 131 is a prime number.

(c) 147

We have 147 = 3 × 7 × 7

So, 147 is not a prime number.

(d) 161

We have 161 = 7 × 23

So, 161 is not a prime number.

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