Question

Pick the number that is not divisible by 7.

• A. 98
• B. 1036
• C. 671
• D. 623

Answer 1

The correct option is C 671

The divisibility rule for 7 states that if a number is divisible by 7 ,then the result obtained by subtracting double the last digit from the remaining number should be 0 or divisible by 7.

623: (3 $\times$ 2) = 6 and 62 - 6 = 56. 56 is divisible by 7. Hence 623 is divisible by 7.

1036: (6 $\times$ 2) = 12 and 103 - 12 = 91. 91 is divisible by 7. Hence 1036 is divisible by 7.

98 : (8 $\times$ 2) = 16 and 16 - 9 = 7. 7 is divisible by 7. Hence 98 is divisible by 7.

671: (1 $\times$ 2) = 2 and 67 - 2 = 65. 65 is not divisible by 7. Hence 671 is not divisible by 7.