question_answer 1)

Which of the following numbers are prime? (a) 23                                     (b) 51                                    (c) 37                                     (d) 26 TIPS To check these given numbers, firstly we divide each number individually by the prime numbers, less than each. If any number is not completely divided by prime numbers, it would be a prime number.

Answer:

                (a) We find that 23 is not exactly divisible; by any of the prime numbers 2, 3, 5, 7, 11, 17 and 19. So, it is a prime number. (b) We find that 51 is divisible by 3. So, it is not a prime number. (c) We find that 37 is not exactly divisible by any of the prime numbers 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 and 31. So, it is a prime number. (d) We find that 26 is exactly divisible by 2 and 13. So, it is not a prime number.