Let's roll up our sleeves and solve this. We have 678 and we're going to multiply it by 11, essentially adding 678 to itself 11 times.
Step 1: 0 + 678 = 678
Step 2: 678 + 678 = 1356
Step 3: 1356 + 678 = 2034
Step 4: 2034 + 678 = 2712
Step 5: 2712 + 678 = 3390
Step 6: 3390 + 678 = 4068
Step 7: 4068 + 678 = 4746
Step 8: 4746 + 678 = 5424
Step 9: 5424 + 678 = 6102
Step 10: 6102 + 678 = 6780
Step 11: 6780 + 678 = 7458

So, 678*11 = 7458