Sure thing, let's get straight to it. We start with 91 and we're going to multiply it by 120, which means adding 91 to itself 120 times.
Step 1: 0 + 91 = 91
Step 2: 91 + 91 = 182
Step 3: 182 + 91 = 273
Step 4: 273 + 91 = 364
Step 5: 364 + 91 = 455
Step 6: 455 + 91 = 546
Step 7: 546 + 91 = 637
Step 8: 637 + 91 = 728
Step 9: 728 + 91 = 819
Step 10: 819 + 91 = 910
Step 11: 910 + 91 = 1001
Step 12: 1001 + 91 = 1092
Step 13: 1092 + 91 = 1183
Step 14: 1183 + 91 = 1274
Step 15: 1274 + 91 = 1365
Step 16: 1365 + 91 = 1456
Step 17: 1456 + 91 = 1547
Step 18: 1547 + 91 = 1638
Step 19: 1638 + 91 = 1729
Step 20: 1729 + 91 = 1820
Step 21: 1820 + 91 = 1911
Step 22: 1911 + 91 = 2002
Step 23: 2002 + 91 = 2093
Step 24: 2093 + 91 = 2184
Step 25: 2184 + 91 = 2275
Step 26: 2275 + 91 = 2366
Step 27: 2366 + 91 = 2457
Step 28: 2457 + 91 = 2548
Step 29: 2548 + 91 = 2639
Step 30: 2639 + 91 = 2730
Step 31: 2730 + 91 = 2821
Step 32: 2821 + 91 = 2912
Step 33: 2912 + 91 = 3003
Step 34: 3003 + 91 = 3094
Step 35: 3094 + 91 = 3185
Step 36: 3185 + 91 = 3276
Step 37: 3276 + 91 = 3367
Step 38: 3367 + 91 = 3458
Step 39: 3458 + 91 = 3549
Step 40: 3549 + 91 = 3640
Step 41: 3640 + 91 = 3731
Step 42: 3731 + 91 = 3822
Step 43: 3822 + 91 = 3913
Step 44: 3913 + 91 = 4004
Step 45: 4004 + 91 = 4095
Step 46: 4095 + 91 = 4186
Step 47: 4186 + 91 = 4277
Step 48: 4277 + 91 = 4368
Step 49: 4368 + 91 = 4459
Step 50: 4459 + 91 = 4550
Step 51: 4550 + 91 = 4641
Step 52: 4641 + 91 = 4732
Step 53: 4732 + 91 = 4823
Step 54: 4823 + 91 = 4914
Step 55: 4914 + 91 = 5005
Step 56: 5005 + 91 = 5096
Step 57: 5096 + 91 = 5187
Step 58: 5187 + 91 = 5278
Step 59: 5278 + 91 = 5369
Step 60: 5369 + 91 = 5460
Step 61: 5460 + 91 = 5551
Step 62: 5551 + 91 = 5642
Step 63: 5642 + 91 = 5733
Step 64: 5733 + 91 = 5824
Step 65: 5824 + 91 = 5915
Step 66: 5915 + 91 = 6006
Step 67: 6006 + 91 = 6097
Step 68: 6097 + 91 = 6188
Step 69: 6188 + 91 = 6279
Step 70: 6279 + 91 = 6370
Step 71: 6370 + 91 = 6461
Step 72: 6461 + 91 = 6552
Step 73: 6552 + 91 = 6643
Step 74: 6643 + 91 = 6734
Step 75: 6734 + 91 = 6825
Step 76: 6825 + 91 = 6916
Step 77: 6916 + 91 = 7007
Step 78: 7007 + 91 = 7098
Step 79: 7098 + 91 = 7189
Step 80: 7189 + 91 = 7280
Step 81: 7280 + 91 = 7371
Step 82: 7371 + 91 = 7462
Step 83: 7462 + 91 = 7553
Step 84: 7553 + 91 = 7644
Step 85: 7644 + 91 = 7735
Step 86: 7735 + 91 = 7826
Step 87: 7826 + 91 = 7917
Step 88: 7917 + 91 = 8008
Step 89: 8008 + 91 = 8099
Step 90: 8099 + 91 = 8190
Step 91: 8190 + 91 = 8281
Step 92: 8281 + 91 = 8372
Step 93: 8372 + 91 = 8463
Step 94: 8463 + 91 = 8554
Step 95: 8554 + 91 = 8645
Step 96: 8645 + 91 = 8736
Step 97: 8736 + 91 = 8827
Step 98: 8827 + 91 = 8918
Step 99: 8918 + 91 = 9009
Step 100: 9009 + 91 = 9100
Step 101: 9100 + 91 = 9191
Step 102: 9191 + 91 = 9282
Step 103: 9282 + 91 = 9373
Step 104: 9373 + 91 = 9464
Step 105: 9464 + 91 = 9555
Step 106: 9555 + 91 = 9646
Step 107: 9646 + 91 = 9737
Step 108: 9737 + 91 = 9828
Step 109: 9828 + 91 = 9919
Step 110: 9919 + 91 = 10010
Step 111: 10010 + 91 = 10101
Step 112: 10101 + 91 = 10192
Step 113: 10192 + 91 = 10283
Step 114: 10283 + 91 = 10374
Step 115: 10374 + 91 = 10465
Step 116: 10465 + 91 = 10556
Step 117: 10556 + 91 = 10647
Step 118: 10647 + 91 = 10738
Step 119: 10738 + 91 = 10829
Step 120: 10829 + 91 = 10920

So, 91*120 = 10920