Question

Jairyll is thinking a composite number between 60 and 70. The number has prime factors that have a sum of 12. What is jairyll's number? ​

Answer 1

the answer is 64

because 6+4=12

and 64 is a factor of prime number

Answer 2

Given:

• A composite number between 60 and 70.
• The number has prime factors that have a sum of 12

To Find:

The composite number

Solution:

Let the composite number be X

X lies between 60 and 70

Possible values of X ⇒

61, 62, 63, 64, 65, 66, 67, 68, 69

Eliminate values according to the condition ⇒

• The number has prime factors
• The sum of prime factors is to be 12

(Now check which number satisfies these conditions)

Numbers with their prime factors & (sum of prime factors):

61 = 61 * 1                          (61 + 1 = 62)

62 = 31 * 2                         (31 + 2 = 33)

63 = 7 * 3 * 3                     (7 + 3 + 3 = 13)

64 = 2 * 2 * 2 * 2 * 2 * 2    (2 * 6 = 12)

65 = 13 * 5                         (13 + 5 = 18)

66 = 11 * 6                          (11 + 6 = 17)

67 = 67 * 1                          (67 + 1 = 68)

68 = 17 * 2 * 2                    (17 + 2 + 2 = 21)

69 = 23 * 3                         (23 + 3 = 26)

We can see the sum of the prime factors of the number "64" adds up to 12.

Hence Jairyll's number is 64.