OK, let's crack this. We're given 587 and our task is to multiply it by 20. Essentially, we'll be adding 587 to itself 20 times.
Step 1: 0 + 587 = 587
Step 2: 587 + 587 = 1174
Step 3: 1174 + 587 = 1761
Step 4: 1761 + 587 = 2348
Step 5: 2348 + 587 = 2935
Step 6: 2935 + 587 = 3522
Step 7: 3522 + 587 = 4109
Step 8: 4109 + 587 = 4696
Step 9: 4696 + 587 = 5283
Step 10: 5283 + 587 = 5870
Step 11: 5870 + 587 = 6457
Step 12: 6457 + 587 = 7044
Step 13: 7044 + 587 = 7631
Step 14: 7631 + 587 = 8218
Step 15: 8218 + 587 = 8805
Step 16: 8805 + 587 = 9392
Step 17: 9392 + 587 = 9979
Step 18: 9979 + 587 = 10566
Step 19: 10566 + 587 = 11153
Step 20: 11153 + 587 = 11740

So, 587*20 = 11740