Using all the digits from 1 to 6 once only, make two numbers which multiplied together give the largest number possible?

Answer 1

542 X 631 = 342002 is the highest number possible
If we pick numbers as shown below we end up loosing on the max number achievable as the asymmetry increases.
63 X 5421 = 341523
6 X 54321 = 325926.

Answer 2

Answer:
542 X 631 = 342002 is the highest number possible