question_answer 15)

Write five pairs of prime numbers less than 20, whose sum is divisible by 5. (Hint 3 + 7 = 10)

Answer:

                Prime numbers less than 20 are 2, 3, 5, 7, 11, 13, 17 and 19. Here,     2 + 3 = 5 (divisible by 5);                2 + 13 = 15 (divisible by 5) 3 + 7 = 10 (divisible by 5);              3 + 17 = 20 (divisible by 5) 7 + 13 = 20 (divisible by 5) Hence, five pairs of prime numbers whose sum is divisible by 5 are (i) 2, 3                    (ii) 2, 13                (iii) 3, 7                  (iv) 3, 17    (v) 7, 13