M4maths Previous Puzzles

07 Feb 2018 Divisibility

How many numbers between 1 and 100 (inclusive) are divisible by 9 or 4?

OPtion

1) 32
2) 24
3) 33
4) 36
5) 28
6) 34
7) 35
8) 26
9) 31
10) None of these

Solution

There are 11 numbers divisible by 9 between 1 and 100, and 25 numbers divisible by 4 between 1 and 100.

So there are 11 + 25 = 36, so 36 numbers divisible by one or the other, but this also includes every number which is divisible by both 9 and 4 twice.
So, for example, 36 and 72 is counted once as a number divisible by 9, and then again as a number divisible by 4. Count of such number which are counted twice 2

So answer is 11+25-2 =34

Correct Option: 6 Best Solution (0)