900
900000
there are 89 twodigits in whole numbers
Exactly 2: 243 of them.
27
how many numbers exactly have 4 digits ? 8900, 8999, 9000, 9999
90 of them.
There are 90 of them.
900
900000
There are 900 three-digit numbers, ranging from 100 to 999.
90000 of them.
there are 89 twodigits in whole numbers
90
900, all numbers from 100 to 999 inclusive.
Assuming that 001, 080, etc are not allowed (that is a leading zero or two is not permitted), the smallest number with exactly three digits is 100. The largest number with exactly three digits is 999. So there are 999 - 100 + 1 = 900 numbers with exactly three digits.
Exactly 2: 243 of them.