625. Here's how:
There are five odd digits {1,3,5,7,9} so our numbers will be made using only these digits. This is the same number of possibilities as if you had a base 5 number system where the allowed digits are {0,1,2,3,4}. For a 1 digit base-5, there are 5 possibilities, for a two digit base-5 there are 5² = 25 possibilities, so for a 4-digit, there are 5^4 = 625possible. This is the same number you will have with only using odd digits.
There are 45 such numbers.
45 of them.
2,4,6,8,10,12,14,16,18
There are 5760 such numbers.
There are 25 possibilities fitting those rules.
There are 17 such numbers.
There are 45 such numbers.
450 whole numbers.
45
45 of them.
450
450
This is not possible, since there are only five single digit odd numbers, which are 1, 3, 5, 7 and 9.
450... There are 500 odd numbers from 000 to 999 inclusive. From 000 to 099, there are 50 odd numbers. 500 - 50 = 450.
Nope. 2 or more digit odd numbers one digit are only 1,3,5,7, and 9, NOT 2,4,6,8,0 . the ten digits ans hundreds and up can have even numbers like 43, or 4423.
There are only five distinct odd digits.
All of them. There are roughly 45,000 5-digit odd numbers. None of them end in 0.