Answer:
3000
Step-by-step explanation:
There are 5 odd digits, so 5^3 = 125 ways to have 3 odd digits.
Given 3 odd digits, the first digit can be even, but not zero, so there are 4 ways to do that.
The second, third, or fourth digits can be even 5 ways, so there are ...
125(4 +5 +5 +5) = 2375
ways to have 3 odd digits in a 4-digit number.
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There are 5^4 = 625 ways to have 4 odd digits.
The number of 4-digit numbers with 3 or 4 odd digits is ...
2375 +625 = 3000
