How many positive 4-digit integers contain the digit grouping 73 at least once, or the numbers 7 or 3 once? For instance, 2738 and 7344 are two such integers to include.
+876 73_ _: 8*8
_ 73 _: 7*8
_ _ 73: 7*8
7373: 1
No 7 or 3: 7*8*8*8
8*8+7*8+7*8+1+7*8*8*8
I am not evaluating that, heavens.
