Question

Question 8 Which of the following numbers are prime? (a) 23 (b) 51 (c) 37 (d) 26

Class 6 - Math - Playing with Numbers Page 53

Answer 1

Prime Number- Which have no factor instead 1 and itself. By Euclid's division lemma.
c= aq+r

here,

51= 17×3 (and vice-versa)

in 37 it has no factor since there remains a remainder in this case...

37 = 18×2+1

23= 10×2+3 , 5×4+3

so 37 and 23 are prime in this case, but not 23 cause it has two subfactor with same remainder therefore 37 is a prime number.

Answer 2

Solution :-

A Prime number can be divided, without any remainder only by itself and by 1.

Examples of prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 ............ 

Now, answer to the above question.

a) 23 = 23 is a prime number because it can be divided only by 23 and by 1.

b) 51 = 51 is not a prime number because it has 3 and 17 as its factors other than 1 and 51. It means 51 is divisible by 3 and 17 also. So, it is a composite number.

c) 37 = 37 is a prime number because it can be divided only by 1 and by 37. 

d) 26 = 26 is not a prime number because it has 2 and 13 as its factors other than 1 and 26. It means 26 is divisible by 2 and 13 also. So, it is a composite number.

So out of the given four numbers (a) 23 and (b) 37 are prime numbers.

Answer.