Sure thing! We've got 688 and we're gonna multiply it by 20. That's the same as adding 688 to itself 20 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
Step 6: 3440 + 688 = 4128
Step 7: 4128 + 688 = 4816
Step 8: 4816 + 688 = 5504
Step 9: 5504 + 688 = 6192
Step 10: 6192 + 688 = 6880
Step 11: 6880 + 688 = 7568
Step 12: 7568 + 688 = 8256
Step 13: 8256 + 688 = 8944
Step 14: 8944 + 688 = 9632
Step 15: 9632 + 688 = 10320
Step 16: 10320 + 688 = 11008
Step 17: 11008 + 688 = 11696
Step 18: 11696 + 688 = 12384
Step 19: 12384 + 688 = 13072
Step 20: 13072 + 688 = 13760

So, 688*20 = 13760