Since it is a four-digit integer, A cannot be 0.
The digits that are allowed are 0, 1, 2, 3, 4, 6, 7, 8, 9. There are 9 possible digits.
For the first digit A, we cannot use 0 or 5, so there are 8 choices.
For the second digit B, we cannot use 5, so there are 9
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