The correct option is D 623
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 × 2) = 6 and 62 - 6 = 56. 56 is divisible by 7.
Hence 623 is divisible by 7.
178:
(8 × 2) = 16 and 17 - 16 = 1.
Hence 178 is not divisible by 7.
671:
(1 × 2) = 2 and 67 - 2 = 65.
65 is not divisible by 7.
Hence 671 is not divisible by 7.
533:
(3 × 2) = 6 and 53 - 6 = 47. 47 is not divisible by 7. Hence 533 is not divisible by 7.
∴623 is the only number among the given which is divisible by 7.