SOLUTION: How many two-digit positive integers less than 100 have the units digit greater than the ten digit ?

12 thru 19, that's 8
23 thru 29, that's 7
34 thru 39, that's 6
45 thru 49, that's 5
56 thru 59, that's 4
67 thru 69, that's 3
78 thru 79, that's 2
        89, that's 1
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            total 36


Edwin