OK, let's crack this. We're given 391 and our task is to multiply it by 8. Essentially, we'll be adding 391 to itself 8 times.
Step 1: 0 + 391 = 391
Step 2: 391 + 391 = 782
Step 3: 782 + 391 = 1173
Step 4: 1173 + 391 = 1564
Step 5: 1564 + 391 = 1955
Step 6: 1955 + 391 = 2346
Step 7: 2346 + 391 = 2737
Step 8: 2737 + 391 = 3128

So, 391*8 = 3128