How many multiples of 9 are between 100,000 and 100,185?

floor((100185-100000)÷9 + 1)=21

Actually, the closest multiples are 100008 and 100185, and when divided by 9, it is from 11112 -> 11131, or 112 -> 131, or 12 -> 31, or 1 ->20

Therefore, there are 20 multiples of 9 between 100,000 and 100,185