Let's get this math done. We have 121 and we're going to multiply it by 20. This is the same as taking 121 and adding it to itself 20 times.
Step 1: 0 + 121 = 121
Step 2: 121 + 121 = 242
Step 3: 242 + 121 = 363
Step 4: 363 + 121 = 484
Step 5: 484 + 121 = 605
Step 6: 605 + 121 = 726
Step 7: 726 + 121 = 847
Step 8: 847 + 121 = 968
Step 9: 968 + 121 = 1089
Step 10: 1089 + 121 = 1210
Step 11: 1210 + 121 = 1331
Step 12: 1331 + 121 = 1452
Step 13: 1452 + 121 = 1573
Step 14: 1573 + 121 = 1694
Step 15: 1694 + 121 = 1815
Step 16: 1815 + 121 = 1936
Step 17: 1936 + 121 = 2057
Step 18: 2057 + 121 = 2178
Step 19: 2178 + 121 = 2299
Step 20: 2299 + 121 = 2420

So, 121*20 = 2420