i have seen a lot of this question and i have use a type but not sure about it.
Positives numbers that are even, smaller than 100000, and which have at least one instance of the digit 5 or 7
What about it this guys,if you could solve it simple and clear it.Cause what i have done alone it doesn't lead to nowhere.Thanks in advance.If you could tell me how to think in this case i will be greatful.
Your question is about 5 digit numbers. The last digit is even and one or more of the first 4 digits is 5 or 7. To solve this, first get the number of 4 digit numbers where none of the digits is 5 or 7. This is simply $8^4=4096$. Therefore there are 5904 4 digit numbers containing 5 or 7. Since the last digit must be even, the total you want is 29520.