Ten digits total, including the zero at the beginning.
i.e. these would be valid:
0xx xxxxxxx
+31 xx xxxxxxx
the answer is get a life
9
10 digits are numbers in the billions.
there are 899 whole numbers that have three digits.
525
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
-99
two
99999
how many numbers exactly have 4 digits ? 8900, 8999, 9000, 9999
17 digits
Numbers above 99 and under 1000 are 3-digits, all 900 of them.