How bout this:
In the series in which 42 was the answer, the question emerged "what is 6x9?" Do the computation in base 13. That is, put the "4" is in the 13's place, not in the tens place. So to convert 42 in base 13 to its equivalent in base 10, that we will more easily understand:
in base 13, 42 = 4x13 + 2x1 = 52+2 = 54 in base ten= 6x9 so 6x9=42 if computed in base 13.
KC