Question
How many 3-digit numbers that are divisible neither by 4 nor by 6 are there?
Answers
Sila
(A) 825 (B) 720 (C) 699 (D) 600 (E) None of the above
oobleck
There are 900 3-digit numbers.
900/4 = ?
900/6 = ?
But if you count all those, you have counted twice all those that are multiples of 24, so subtract those off.
Now you have a count of all those divisible by 4 or 6 or both.
Subtract that from 900.
900/4 = ?
900/6 = ?
But if you count all those, you have counted twice all those that are multiples of 24, so subtract those off.
Now you have a count of all those divisible by 4 or 6 or both.
Subtract that from 900.