With base one million, you can create one nonillion different numbers; using the traditional decimal (base ten) system, you can form 100 thousand different numbers.
5 digits will suffice.
There are 720 of them. The three digit counting numbers are 100-999. All multiples of 5 have their last digit as 0 or 5. There are 9 possible numbers {1-9} for the first digit, There are 10 possible numbers {0-9} for each of the first digits, There are 8 possible numbers {1-4, 6-9} for each of the first two digits, Making 9 x 10 x 8 = 720 possible 3 digit counting numbers not multiples of 5.
5
The natural numbers, in normal usage, have only 9 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.The natural numbers, in normal usage, have only 9 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.The natural numbers, in normal usage, have only 9 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.The natural numbers, in normal usage, have only 9 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.
8,ooo
99999
There are 90000 5-digit numbers.
There are 5*4*3 = 60 such numbers.
10001
one
All of them.
90000 of them.
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
500
There are 5460 five digit numbers with a digit sum of 22.
Assuming that the first digit can't be zero: If repetition of digits is permitted: (5 x 6 x 6) = 180 numbers of 3 digits. If repetition of digits is not permitted: (5 x 5 x 4) = 100 numbers of 3 digits.
5 digits will suffice.