ANSWERS: 4

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90

If we know the first two digits, we can find out the last two digits: ab?? > abba. There are 100 combinations of 2digits from 00 to 99, but the first 10 (00 to 09) do not yield 2digit numbers. So we have 90 two digit numbers and so 90 such 4digit numbers.

1262017 The first digit can be 1 thru 9 and the second digit can be 0 thru 9 so possible combinations are 9 x 10 = 90
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