5 | 1 6 11 6 -1680 | | 5 55 330 1680 --------------------------------- 1 11 66 336 0
Take the square root of 1680:= 40.99 (approx.) From this, it is clear that the numbers are around of 6 and 7. Check 5, 6, 7 and 8: 5*6*7*8 = 1680. Answer. The numbers are 5, 6, 7 and 8.