how many positive 3 - digit integers are divisible by both 3 and 7 ?  Choices:
A) 43	B) 45	C) 47	D) 50	E) 52

Rationale: a number to be divisible by both 3 and 7 should be divisible by the least common multiple of 3 and 7 so by 21 . multiples of 21 between 100 and 999 , inclusive is ( last - first ) / multiple + 1 = ( 987 - 105 ) / 21 + 1 = 42 + 1 = 43 answer : a .
Answer: A