OK, let's crack this. We're given 138 and our task is to multiply it by 8. Essentially, we'll be adding 138 to itself 8 times.
Step 1: 0 + 138 = 138
Step 2: 138 + 138 = 276
Step 3: 276 + 138 = 414
Step 4: 414 + 138 = 552
Step 5: 552 + 138 = 690
Step 6: 690 + 138 = 828
Step 7: 828 + 138 = 966
Step 8: 966 + 138 = 1104

So, 138*8 = 1104