Problem: what is the number of integers from 1 to 1000 ( inclusive ) that are divisible by neither 20 nor by 35 ?
Rationale: "in 1000 consecutive numbers , number of multiples of 20 = 1000 / 20 = 50 ( ignore decimals ) in 1000 consecutive numbers , number of multiples of 35 = 1000 / 35 = 28 number of multiples of 20 * 35 i . e . 700 = 1000 / 700 = 1 number of integers from 1 to 1000 that are divisible by neither 20 nor by 35 = 1000 - ( 50 + 28 - 1 ) { using the concept of sets here ) = 923 answer is d"
annotated_formula: subtract(1000, subtract(add(divide(1000, 20), divide(1000, 35)), divide(1000, multiply(20, 35))))