Let's roll up our sleeves and solve this. We have 809 and we're going to multiply it by 150, essentially adding 809 to itself 150 times.
Step 1: 0 + 809 = 809
Step 2: 809 + 809 = 1618
Step 3: 1618 + 809 = 2427
Step 4: 2427 + 809 = 3236
Step 5: 3236 + 809 = 4045
Step 6: 4045 + 809 = 4854
Step 7: 4854 + 809 = 5663
Step 8: 5663 + 809 = 6472
Step 9: 6472 + 809 = 7281
Step 10: 7281 + 809 = 8090
Step 11: 8090 + 809 = 8899
Step 12: 8899 + 809 = 9708
Step 13: 9708 + 809 = 10517
Step 14: 10517 + 809 = 11326
Step 15: 11326 + 809 = 12135
Step 16: 12135 + 809 = 12944
Step 17: 12944 + 809 = 13753
Step 18: 13753 + 809 = 14562
Step 19: 14562 + 809 = 15371
Step 20: 15371 + 809 = 16180
Step 21: 16180 + 809 = 16989
Step 22: 16989 + 809 = 17798
Step 23: 17798 + 809 = 18607
Step 24: 18607 + 809 = 19416
Step 25: 19416 + 809 = 20225
Step 26: 20225 + 809 = 21034
Step 27: 21034 + 809 = 21843
Step 28: 21843 + 809 = 22652
Step 29: 22652 + 809 = 23461
Step 30: 23461 + 809 = 24270
Step 31: 24270 + 809 = 25079
Step 32: 25079 + 809 = 25888
Step 33: 25888 + 809 = 26697
Step 34: 26697 + 809 = 27506
Step 35: 27506 + 809 = 28315
Step 36: 28315 + 809 = 29124
Step 37: 29124 + 809 = 29933
Step 38: 29933 + 809 = 30742
Step 39: 30742 + 809 = 31551
Step 40: 31551 + 809 = 32360
Step 41: 32360 + 809 = 33169
Step 42: 33169 + 809 = 33978
Step 43: 33978 + 809 = 34787
Step 44: 34787 + 809 = 35596
Step 45: 35596 + 809 = 36405
Step 46: 36405 + 809 = 37214
Step 47: 37214 + 809 = 38023
Step 48: 38023 + 809 = 38832
Step 49: 38832 + 809 = 39641
Step 50: 39641 + 809 = 40450
Step 51: 40450 + 809 = 41259
Step 52: 41259 + 809 = 42068
Step 53: 42068 + 809 = 42877
Step 54: 42877 + 809 = 43686
Step 55: 43686 + 809 = 44495
Step 56: 44495 + 809 = 45304
Step 57: 45304 + 809 = 46113
Step 58: 46113 + 809 = 46922
Step 59: 46922 + 809 = 47731
Step 60: 47731 + 809 = 48540
Step 61: 48540 + 809 = 49349
Step 62: 49349 + 809 = 50158
Step 63: 50158 + 809 = 50967
Step 64: 50967 + 809 = 51776
Step 65: 51776 + 809 = 52585
Step 66: 52585 + 809 = 53394
Step 67: 53394 + 809 = 54203
Step 68: 54203 + 809 = 55012
Step 69: 55012 + 809 = 55821
Step 70: 55821 + 809 = 56630
Step 71: 56630 + 809 = 57439
Step 72: 57439 + 809 = 58248
Step 73: 58248 + 809 = 59057
Step 74: 59057 + 809 = 59866
Step 75: 59866 + 809 = 60675
Step 76: 60675 + 809 = 61484
Step 77: 61484 + 809 = 62293
Step 78: 62293 + 809 = 63102
Step 79: 63102 + 809 = 63911
Step 80: 63911 + 809 = 64720
Step 81: 64720 + 809 = 65529
Step 82: 65529 + 809 = 66338
Step 83: 66338 + 809 = 67147
Step 84: 67147 + 809 = 67956
Step 85: 67956 + 809 = 68765
Step 86: 68765 + 809 = 69574
Step 87: 69574 + 809 = 70383
Step 88: 70383 + 809 = 71192
Step 89: 71192 + 809 = 72001
Step 90: 72001 + 809 = 72810
Step 91: 72810 + 809 = 73619
Step 92: 73619 + 809 = 74428
Step 93: 74428 + 809 = 75237
Step 94: 75237 + 809 = 76046
Step 95: 76046 + 809 = 76855
Step 96: 76855 + 809 = 77664
Step 97: 77664 + 809 = 78473
Step 98: 78473 + 809 = 79282
Step 99: 79282 + 809 = 80091
Step 100: 80091 + 809 = 80900
Step 101: 80900 + 809 = 81709
Step 102: 81709 + 809 = 82518
Step 103: 82518 + 809 = 83327
Step 104: 83327 + 809 = 84136
Step 105: 84136 + 809 = 84945
Step 106: 84945 + 809 = 85754
Step 107: 85754 + 809 = 86563
Step 108: 86563 + 809 = 87372
Step 109: 87372 + 809 = 88181
Step 110: 88181 + 809 = 88990
Step 111: 88990 + 809 = 89799
Step 112: 89799 + 809 = 90608
Step 113: 90608 + 809 = 91417
Step 114: 91417 + 809 = 92226
Step 115: 92226 + 809 = 93035
Step 116: 93035 + 809 = 93844
Step 117: 93844 + 809 = 94653
Step 118: 94653 + 809 = 95462
Step 119: 95462 + 809 = 96271
Step 120: 96271 + 809 = 97080
Step 121: 97080 + 809 = 97889
Step 122: 97889 + 809 = 98698
Step 123: 98698 + 809 = 99507
Step 124: 99507 + 809 = 100316
Step 125: 100316 + 809 = 101125
Step 126: 101125 + 809 = 101934
Step 127: 101934 + 809 = 102743
Step 128: 102743 + 809 = 103552
Step 129: 103552 + 809 = 104361
Step 130: 104361 + 809 = 105170
Step 131: 105170 + 809 = 105979
Step 132: 105979 + 809 = 106788
Step 133: 106788 + 809 = 107597
Step 134: 107597 + 809 = 108406
Step 135: 108406 + 809 = 109215
Step 136: 109215 + 809 = 110024
Step 137: 110024 + 809 = 110833
Step 138: 110833 + 809 = 111642
Step 139: 111642 + 809 = 112451
Step 140: 112451 + 809 = 113260
Step 141: 113260 + 809 = 114069
Step 142: 114069 + 809 = 114878
Step 143: 114878 + 809 = 115687
Step 144: 115687 + 809 = 116496
Step 145: 116496 + 809 = 117305
Step 146: 117305 + 809 = 118114
Step 147: 118114 + 809 = 118923
Step 148: 118923 + 809 = 119732
Step 149: 119732 + 809 = 120541
Step 150: 120541 + 809 = 121350

So, 809*150 = 121350