What digits might composite numbers greater than 10 have in the ones place. 12345.?

Composite numbers can have any digit in the ones place:

All multiples of 3 greater than 10 will be composite numbers (the first one being 3×4 = 12).

The last digit of the multiples of 3 follow the pattern (starting at 12, ending at 39): {2, 5, 8, 1, 4, 7, 0, 3, 6, 9} which includes all the digits {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}.

Thus the last digit of composite numbers greater than 10 can contain any digit.