OK, let's work through this together. We're starting with 451 and we're going to multiply it by 158, which means we add 451 to itself 158 times.
Step 1: 0 + 451 = 451
Step 2: 451 + 451 = 902
Step 3: 902 + 451 = 1353
Step 4: 1353 + 451 = 1804
Step 5: 1804 + 451 = 2255
Step 6: 2255 + 451 = 2706
Step 7: 2706 + 451 = 3157
Step 8: 3157 + 451 = 3608
Step 9: 3608 + 451 = 4059
Step 10: 4059 + 451 = 4510
Step 11: 4510 + 451 = 4961
Step 12: 4961 + 451 = 5412
Step 13: 5412 + 451 = 5863
Step 14: 5863 + 451 = 6314
Step 15: 6314 + 451 = 6765
Step 16: 6765 + 451 = 7216
Step 17: 7216 + 451 = 7667
Step 18: 7667 + 451 = 8118
Step 19: 8118 + 451 = 8569
Step 20: 8569 + 451 = 9020
Step 21: 9020 + 451 = 9471
Step 22: 9471 + 451 = 9922
Step 23: 9922 + 451 = 10373
Step 24: 10373 + 451 = 10824
Step 25: 10824 + 451 = 11275
Step 26: 11275 + 451 = 11726
Step 27: 11726 + 451 = 12177
Step 28: 12177 + 451 = 12628
Step 29: 12628 + 451 = 13079
Step 30: 13079 + 451 = 13530
Step 31: 13530 + 451 = 13981
Step 32: 13981 + 451 = 14432
Step 33: 14432 + 451 = 14883
Step 34: 14883 + 451 = 15334
Step 35: 15334 + 451 = 15785
Step 36: 15785 + 451 = 16236
Step 37: 16236 + 451 = 16687
Step 38: 16687 + 451 = 17138
Step 39: 17138 + 451 = 17589
Step 40: 17589 + 451 = 18040
Step 41: 18040 + 451 = 18491
Step 42: 18491 + 451 = 18942
Step 43: 18942 + 451 = 19393
Step 44: 19393 + 451 = 19844
Step 45: 19844 + 451 = 20295
Step 46: 20295 + 451 = 20746
Step 47: 20746 + 451 = 21197
Step 48: 21197 + 451 = 21648
Step 49: 21648 + 451 = 22099
Step 50: 22099 + 451 = 22550
Step 51: 22550 + 451 = 23001
Step 52: 23001 + 451 = 23452
Step 53: 23452 + 451 = 23903
Step 54: 23903 + 451 = 24354
Step 55: 24354 + 451 = 24805
Step 56: 24805 + 451 = 25256
Step 57: 25256 + 451 = 25707
Step 58: 25707 + 451 = 26158
Step 59: 26158 + 451 = 26609
Step 60: 26609 + 451 = 27060
Step 61: 27060 + 451 = 27511
Step 62: 27511 + 451 = 27962
Step 63: 27962 + 451 = 28413
Step 64: 28413 + 451 = 28864
Step 65: 28864 + 451 = 29315
Step 66: 29315 + 451 = 29766
Step 67: 29766 + 451 = 30217
Step 68: 30217 + 451 = 30668
Step 69: 30668 + 451 = 31119
Step 70: 31119 + 451 = 31570
Step 71: 31570 + 451 = 32021
Step 72: 32021 + 451 = 32472
Step 73: 32472 + 451 = 32923
Step 74: 32923 + 451 = 33374
Step 75: 33374 + 451 = 33825
Step 76: 33825 + 451 = 34276
Step 77: 34276 + 451 = 34727
Step 78: 34727 + 451 = 35178
Step 79: 35178 + 451 = 35629
Step 80: 35629 + 451 = 36080
Step 81: 36080 + 451 = 36531
Step 82: 36531 + 451 = 36982
Step 83: 36982 + 451 = 37433
Step 84: 37433 + 451 = 37884
Step 85: 37884 + 451 = 38335
Step 86: 38335 + 451 = 38786
Step 87: 38786 + 451 = 39237
Step 88: 39237 + 451 = 39688
Step 89: 39688 + 451 = 40139
Step 90: 40139 + 451 = 40590
Step 91: 40590 + 451 = 41041
Step 92: 41041 + 451 = 41492
Step 93: 41492 + 451 = 41943
Step 94: 41943 + 451 = 42394
Step 95: 42394 + 451 = 42845
Step 96: 42845 + 451 = 43296
Step 97: 43296 + 451 = 43747
Step 98: 43747 + 451 = 44198
Step 99: 44198 + 451 = 44649
Step 100: 44649 + 451 = 45100
Step 101: 45100 + 451 = 45551
Step 102: 45551 + 451 = 46002
Step 103: 46002 + 451 = 46453
Step 104: 46453 + 451 = 46904
Step 105: 46904 + 451 = 47355
Step 106: 47355 + 451 = 47806
Step 107: 47806 + 451 = 48257
Step 108: 48257 + 451 = 48708
Step 109: 48708 + 451 = 49159
Step 110: 49159 + 451 = 49610
Step 111: 49610 + 451 = 50061
Step 112: 50061 + 451 = 50512
Step 113: 50512 + 451 = 50963
Step 114: 50963 + 451 = 51414
Step 115: 51414 + 451 = 51865
Step 116: 51865 + 451 = 52316
Step 117: 52316 + 451 = 52767
Step 118: 52767 + 451 = 53218
Step 119: 53218 + 451 = 53669
Step 120: 53669 + 451 = 54120
Step 121: 54120 + 451 = 54571
Step 122: 54571 + 451 = 55022
Step 123: 55022 + 451 = 55473
Step 124: 55473 + 451 = 55924
Step 125: 55924 + 451 = 56375
Step 126: 56375 + 451 = 56826
Step 127: 56826 + 451 = 57277
Step 128: 57277 + 451 = 57728
Step 129: 57728 + 451 = 58179
Step 130: 58179 + 451 = 58630
Step 131: 58630 + 451 = 59081
Step 132: 59081 + 451 = 59532
Step 133: 59532 + 451 = 59983
Step 134: 59983 + 451 = 60434
Step 135: 60434 + 451 = 60885
Step 136: 60885 + 451 = 61336
Step 137: 61336 + 451 = 61787
Step 138: 61787 + 451 = 62238
Step 139: 62238 + 451 = 62689
Step 140: 62689 + 451 = 63140
Step 141: 63140 + 451 = 63591
Step 142: 63591 + 451 = 64042
Step 143: 64042 + 451 = 64493
Step 144: 64493 + 451 = 64944
Step 145: 64944 + 451 = 65395
Step 146: 65395 + 451 = 65846
Step 147: 65846 + 451 = 66297
Step 148: 66297 + 451 = 66748
Step 149: 66748 + 451 = 67199
Step 150: 67199 + 451 = 67650
Step 151: 67650 + 451 = 68101
Step 152: 68101 + 451 = 68552
Step 153: 68552 + 451 = 69003
Step 154: 69003 + 451 = 69454
Step 155: 69454 + 451 = 69905
Step 156: 69905 + 451 = 70356
Step 157: 70356 + 451 = 70807
Step 158: 70807 + 451 = 71258

So, 451*158 = 71258