Question

Write five pairs of prime number less than 25 whose sum is divisible by 3 ?

Answer 1

Answer:

prime number is not divisible by another number

Step-by-step explanation:

prime number less than 25 is 2,3,5,7,11,13,17,19,23

Answer 2

Answer:

Five pairs of prime numbers less than 25, whose sum is divisible by 3 are

(2,7),(2,13),(2,19),(5,7),(5,13)

Step-by-step explanation:

To find,

Five pairs of prime numbers less than 25 whose sum is divisible by 3

Solution:

The prime numbers less than 25 are

2,3,5,7,11,13,17,19,23

With '2' as one prime number, the pairs of prime numbers such that the sum is divisible by 3 are

(2,7),(2,13),(2,19),

we have,

2+7 = 12, divisible by 3

2+13 = 15, divisible by 3

2+19 = 21, divisible by 3

With '3' as one prime number,  we cannot form a pair such that their sum is divisible by 3

With '5' as one prime number, the pairs of prime numbers such that their sum is divisible by 3 are

(5,7),(5,13)

5+7 = 12, divisible by 3

5+13 = 18, divisible by 3

Hence,

Five pairs of prime numbers less than 25, whose sum is divisible by 3 are

(2,7),(2,13),(2,19),(5,7),(5,13)

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