Let's roll up our sleeves and solve this. We have 517 and we're going to multiply it by 20, essentially adding 517 to itself 20 times.
Step 1: 0 + 517 = 517
Step 2: 517 + 517 = 1034
Step 3: 1034 + 517 = 1551
Step 4: 1551 + 517 = 2068
Step 5: 2068 + 517 = 2585
Step 6: 2585 + 517 = 3102
Step 7: 3102 + 517 = 3619
Step 8: 3619 + 517 = 4136
Step 9: 4136 + 517 = 4653
Step 10: 4653 + 517 = 5170
Step 11: 5170 + 517 = 5687
Step 12: 5687 + 517 = 6204
Step 13: 6204 + 517 = 6721
Step 14: 6721 + 517 = 7238
Step 15: 7238 + 517 = 7755
Step 16: 7755 + 517 = 8272
Step 17: 8272 + 517 = 8789
Step 18: 8789 + 517 = 9306
Step 19: 9306 + 517 = 9823
Step 20: 9823 + 517 = 10340

So, 517*20 = 10340