Let's get this math done. We have 688 and we're going to multiply it by 5. This is the same as taking 688 and adding it to itself 5 times.
Step 1: 0 + 688 = 688
Step 2: 688 + 688 = 1376
Step 3: 1376 + 688 = 2064
Step 4: 2064 + 688 = 2752
Step 5: 2752 + 688 = 3440

So, 688*5 = 3440