OK, let's work through this together. We're starting with 654 and we're going to multiply it by 20, which means we add 654 to itself 20 times.
Step 1: 0 + 654 = 654
Step 2: 654 + 654 = 1308
Step 3: 1308 + 654 = 1962
Step 4: 1962 + 654 = 2616
Step 5: 2616 + 654 = 3270
Step 6: 3270 + 654 = 3924
Step 7: 3924 + 654 = 4578
Step 8: 4578 + 654 = 5232
Step 9: 5232 + 654 = 5886
Step 10: 5886 + 654 = 6540
Step 11: 6540 + 654 = 7194
Step 12: 7194 + 654 = 7848
Step 13: 7848 + 654 = 8502
Step 14: 8502 + 654 = 9156
Step 15: 9156 + 654 = 9810
Step 16: 9810 + 654 = 10464
Step 17: 10464 + 654 = 11118
Step 18: 11118 + 654 = 11772
Step 19: 11772 + 654 = 12426
Step 20: 12426 + 654 = 13080

So, 654*20 = 13080