The sum of the non-prime numbers between 60 and 70, non-inclusive, is  Pick:
A) 387
B) 429
C) 457
D) 499
E) 536

Rationale: "sum of consecutive integers from 61 to 69 , inclusive = = = = > ( a 1 + an ) / 2 * # of terms = ( 61 + 69 ) / 2 * 9 = 65 * 9 = 585 sum of non - prime numbers b / w 60 and 70 , non inclusive = = = > 585 - 128 ( i . e . , 61 + 67 , being the prime # s in the range ) = 457 answer : c"
Answer: C