89999
Any whole number above 99999 has 6 or more digits, and any whole number below 10000 has 4 or less digits. Since there are only whole numbers involved, it is a simple subtraction of 10000 from 99999.
how many numbers exactly have 4 digits ? 8900, 8999, 9000, 9999
there are 89 twodigits in whole numbers
90
890
27
900 of them.
there are 899 whole numbers that have three digits.
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.
All the whole numbers between 99 and 1,000. Simple subtraction will give you a number, if that's what you meant to ask. 900, the numbers above are exclusive.
900
900000
There are 90 of them.