Question

how many numbers are divided by 9 or 11 between 400 to 700

Answer 1

$405and704$

Answer 2

Let’s find LCM (least common multiple) of 9 and 11 to see the least number which is divisible by both 9 and 11.

As we can see only 792 belongs to [400, 800] interval, it’s the least and the last number for this interval.

So we have an answer: only 1 number between 400 and 800 is divisible by both 88 and 72.