Problem: what is the number of integers from 1 to 100 ( inclusive ) that are divisible by neither 5 nor by 6 ?
Rationale: "in 100 consecutive numbers , number of multiples of 5 = 100 / 5 = 20 ( ignore decimals ) in 100 consecutive numbers , number of multiples of 6 = 100 / 6 = 16 number of multiples of 5 * 6 i . e . 30 = 100 / 30 = 3 number of integers from 1 to 100 that are divisible by neither 5 nor by 6 = 100 - ( 29 + 16 - 3 ) { using the concept of sets here ) = 58 answer is c"
annotated_formula: subtract(100, subtract(add(divide(100, 5), divide(100, 6)), divide(100, multiply(5, 6))))