Let's get this math done. We have 831 and we're going to multiply it by 8. This is the same as taking 831 and adding it to itself 8 times.
Step 1: 0 + 831 = 831
Step 2: 831 + 831 = 1662
Step 3: 1662 + 831 = 2493
Step 4: 2493 + 831 = 3324
Step 5: 3324 + 831 = 4155
Step 6: 4155 + 831 = 4986
Step 7: 4986 + 831 = 5817
Step 8: 5817 + 831 = 6648

So, 831*8 = 6648