Let's roll up our sleeves and solve this. We have 621 and we're going to multiply it by 434, essentially adding 621 to itself 434 times.
Step 1: 0 + 621 = 621
Step 2: 621 + 621 = 1242
Step 3: 1242 + 621 = 1863
Step 4: 1863 + 621 = 2484
Step 5: 2484 + 621 = 3105
Step 6: 3105 + 621 = 3726
Step 7: 3726 + 621 = 4347
Step 8: 4347 + 621 = 4968
Step 9: 4968 + 621 = 5589
Step 10: 5589 + 621 = 6210
Step 11: 6210 + 621 = 6831
Step 12: 6831 + 621 = 7452
Step 13: 7452 + 621 = 8073
Step 14: 8073 + 621 = 8694
Step 15: 8694 + 621 = 9315
Step 16: 9315 + 621 = 9936
Step 17: 9936 + 621 = 10557
Step 18: 10557 + 621 = 11178
Step 19: 11178 + 621 = 11799
Step 20: 11799 + 621 = 12420
Step 21: 12420 + 621 = 13041
Step 22: 13041 + 621 = 13662
Step 23: 13662 + 621 = 14283
Step 24: 14283 + 621 = 14904
Step 25: 14904 + 621 = 15525
Step 26: 15525 + 621 = 16146
Step 27: 16146 + 621 = 16767
Step 28: 16767 + 621 = 17388
Step 29: 17388 + 621 = 18009
Step 30: 18009 + 621 = 18630
Step 31: 18630 + 621 = 19251
Step 32: 19251 + 621 = 19872
Step 33: 19872 + 621 = 20493
Step 34: 20493 + 621 = 21114
Step 35: 21114 + 621 = 21735
Step 36: 21735 + 621 = 22356
Step 37: 22356 + 621 = 22977
Step 38: 22977 + 621 = 23598
Step 39: 23598 + 621 = 24219
Step 40: 24219 + 621 = 24840
Step 41: 24840 + 621 = 25461
Step 42: 25461 + 621 = 26082
Step 43: 26082 + 621 = 26703
Step 44: 26703 + 621 = 27324
Step 45: 27324 + 621 = 27945
Step 46: 27945 + 621 = 28566
Step 47: 28566 + 621 = 29187
Step 48: 29187 + 621 = 29808
Step 49: 29808 + 621 = 30429
Step 50: 30429 + 621 = 31050
Step 51: 31050 + 621 = 31671
Step 52: 31671 + 621 = 32292
Step 53: 32292 + 621 = 32913
Step 54: 32913 + 621 = 33534
Step 55: 33534 + 621 = 34155
Step 56: 34155 + 621 = 34776
Step 57: 34776 + 621 = 35397
Step 58: 35397 + 621 = 36018
Step 59: 36018 + 621 = 36639
Step 60: 36639 + 621 = 37260
Step 61: 37260 + 621 = 37881
Step 62: 37881 + 621 = 38502
Step 63: 38502 + 621 = 39123
Step 64: 39123 + 621 = 39744
Step 65: 39744 + 621 = 40365
Step 66: 40365 + 621 = 40986
Step 67: 40986 + 621 = 41607
Step 68: 41607 + 621 = 42228
Step 69: 42228 + 621 = 42849
Step 70: 42849 + 621 = 43470
Step 71: 43470 + 621 = 44091
Step 72: 44091 + 621 = 44712
Step 73: 44712 + 621 = 45333
Step 74: 45333 + 621 = 45954
Step 75: 45954 + 621 = 46575
Step 76: 46575 + 621 = 47196
Step 77: 47196 + 621 = 47817
Step 78: 47817 + 621 = 48438
Step 79: 48438 + 621 = 49059
Step 80: 49059 + 621 = 49680
Step 81: 49680 + 621 = 50301
Step 82: 50301 + 621 = 50922
Step 83: 50922 + 621 = 51543
Step 84: 51543 + 621 = 52164
Step 85: 52164 + 621 = 52785
Step 86: 52785 + 621 = 53406
Step 87: 53406 + 621 = 54027
Step 88: 54027 + 621 = 54648
Step 89: 54648 + 621 = 55269
Step 90: 55269 + 621 = 55890
Step 91: 55890 + 621 = 56511
Step 92: 56511 + 621 = 57132
Step 93: 57132 + 621 = 57753
Step 94: 57753 + 621 = 58374
Step 95: 58374 + 621 = 58995
Step 96: 58995 + 621 = 59616
Step 97: 59616 + 621 = 60237
Step 98: 60237 + 621 = 60858
Step 99: 60858 + 621 = 61479
Step 100: 61479 + 621 = 62100
Step 101: 62100 + 621 = 62721
Step 102: 62721 + 621 = 63342
Step 103: 63342 + 621 = 63963
Step 104: 63963 + 621 = 64584
Step 105: 64584 + 621 = 65205
Step 106: 65205 + 621 = 65826
Step 107: 65826 + 621 = 66447
Step 108: 66447 + 621 = 67068
Step 109: 67068 + 621 = 67689
Step 110: 67689 + 621 = 68310
Step 111: 68310 + 621 = 68931
Step 112: 68931 + 621 = 69552
Step 113: 69552 + 621 = 70173
Step 114: 70173 + 621 = 70794
Step 115: 70794 + 621 = 71415
Step 116: 71415 + 621 = 72036
Step 117: 72036 + 621 = 72657
Step 118: 72657 + 621 = 73278
Step 119: 73278 + 621 = 73899
Step 120: 73899 + 621 = 74520
Step 121: 74520 + 621 = 75141
Step 122: 75141 + 621 = 75762
Step 123: 75762 + 621 = 76383
Step 124: 76383 + 621 = 77004
Step 125: 77004 + 621 = 77625
Step 126: 77625 + 621 = 78246
Step 127: 78246 + 621 = 78867
Step 128: 78867 + 621 = 79488
Step 129: 79488 + 621 = 80109
Step 130: 80109 + 621 = 80730
Step 131: 80730 + 621 = 81351
Step 132: 81351 + 621 = 81972
Step 133: 81972 + 621 = 82593
Step 134: 82593 + 621 = 83214
Step 135: 83214 + 621 = 83835
Step 136: 83835 + 621 = 84456
Step 137: 84456 + 621 = 85077
Step 138: 85077 + 621 = 85698
Step 139: 85698 + 621 = 86319
Step 140: 86319 + 621 = 86940
Step 141: 86940 + 621 = 87561
Step 142: 87561 + 621 = 88182
Step 143: 88182 + 621 = 88803
Step 144: 88803 + 621 = 89424
Step 145: 89424 + 621 = 90045
Step 146: 90045 + 621 = 90666
Step 147: 90666 + 621 = 91287
Step 148: 91287 + 621 = 91908
Step 149: 91908 + 621 = 92529
Step 150: 92529 + 621 = 93150
Step 151: 93150 + 621 = 93771
Step 152: 93771 + 621 = 94392
Step 153: 94392 + 621 = 95013
Step 154: 95013 + 621 = 95634
Step 155: 95634 + 621 = 96255
Step 156: 96255 + 621 = 96876
Step 157: 96876 + 621 = 97497
Step 158: 97497 + 621 = 98118
Step 159: 98118 + 621 = 98739
Step 160: 98739 + 621 = 99360
Step 161: 99360 + 621 = 99981
Step 162: 99981 + 621 = 100602
Step 163: 100602 + 621 = 101223
Step 164: 101223 + 621 = 101844
Step 165: 101844 + 621 = 102465
Step 166: 102465 + 621 = 103086
Step 167: 103086 + 621 = 103707
Step 168: 103707 + 621 = 104328
Step 169: 104328 + 621 = 104949
Step 170: 104949 + 621 = 105570
Step 171: 105570 + 621 = 106191
Step 172: 106191 + 621 = 106812
Step 173: 106812 + 621 = 107433
Step 174: 107433 + 621 = 108054
Step 175: 108054 + 621 = 108675
Step 176: 108675 + 621 = 109296
Step 177: 109296 + 621 = 109917
Step 178: 109917 + 621 = 110538
Step 179: 110538 + 621 = 111159
Step 180: 111159 + 621 = 111780
Step 181: 111780 + 621 = 112401
Step 182: 112401 + 621 = 113022
Step 183: 113022 + 621 = 113643
Step 184: 113643 + 621 = 114264
Step 185: 114264 + 621 = 114885
Step 186: 114885 + 621 = 115506
Step 187: 115506 + 621 = 116127
Step 188: 116127 + 621 = 116748
Step 189: 116748 + 621 = 117369
Step 190: 117369 + 621 = 117990
Step 191: 117990 + 621 = 118611
Step 192: 118611 + 621 = 119232
Step 193: 119232 + 621 = 119853
Step 194: 119853 + 621 = 120474
Step 195: 120474 + 621 = 121095
Step 196: 121095 + 621 = 121716
Step 197: 121716 + 621 = 122337
Step 198: 122337 + 621 = 122958
Step 199: 122958 + 621 = 123579
Step 200: 123579 + 621 = 124200
Step 201: 124200 + 621 = 124821
Step 202: 124821 + 621 = 125442
Step 203: 125442 + 621 = 126063
Step 204: 126063 + 621 = 126684
Step 205: 126684 + 621 = 127305
Step 206: 127305 + 621 = 127926
Step 207: 127926 + 621 = 128547
Step 208: 128547 + 621 = 129168
Step 209: 129168 + 621 = 129789
Step 210: 129789 + 621 = 130410
Step 211: 130410 + 621 = 131031
Step 212: 131031 + 621 = 131652
Step 213: 131652 + 621 = 132273
Step 214: 132273 + 621 = 132894
Step 215: 132894 + 621 = 133515
Step 216: 133515 + 621 = 134136
Step 217: 134136 + 621 = 134757
Step 218: 134757 + 621 = 135378
Step 219: 135378 + 621 = 135999
Step 220: 135999 + 621 = 136620
Step 221: 136620 + 621 = 137241
Step 222: 137241 + 621 = 137862
Step 223: 137862 + 621 = 138483
Step 224: 138483 + 621 = 139104
Step 225: 139104 + 621 = 139725
Step 226: 139725 + 621 = 140346
Step 227: 140346 + 621 = 140967
Step 228: 140967 + 621 = 141588
Step 229: 141588 + 621 = 142209
Step 230: 142209 + 621 = 142830
Step 231: 142830 + 621 = 143451
Step 232: 143451 + 621 = 144072
Step 233: 144072 + 621 = 144693
Step 234: 144693 + 621 = 145314
Step 235: 145314 + 621 = 145935
Step 236: 145935 + 621 = 146556
Step 237: 146556 + 621 = 147177
Step 238: 147177 + 621 = 147798
Step 239: 147798 + 621 = 148419
Step 240: 148419 + 621 = 149040
Step 241: 149040 + 621 = 149661
Step 242: 149661 + 621 = 150282
Step 243: 150282 + 621 = 150903
Step 244: 150903 + 621 = 151524
Step 245: 151524 + 621 = 152145
Step 246: 152145 + 621 = 152766
Step 247: 152766 + 621 = 153387
Step 248: 153387 + 621 = 154008
Step 249: 154008 + 621 = 154629
Step 250: 154629 + 621 = 155250
Step 251: 155250 + 621 = 155871
Step 252: 155871 + 621 = 156492
Step 253: 156492 + 621 = 157113
Step 254: 157113 + 621 = 157734
Step 255: 157734 + 621 = 158355
Step 256: 158355 + 621 = 158976
Step 257: 158976 + 621 = 159597
Step 258: 159597 + 621 = 160218
Step 259: 160218 + 621 = 160839
Step 260: 160839 + 621 = 161460
Step 261: 161460 + 621 = 162081
Step 262: 162081 + 621 = 162702
Step 263: 162702 + 621 = 163323
Step 264: 163323 + 621 = 163944
Step 265: 163944 + 621 = 164565
Step 266: 164565 + 621 = 165186
Step 267: 165186 + 621 = 165807
Step 268: 165807 + 621 = 166428
Step 269: 166428 + 621 = 167049
Step 270: 167049 + 621 = 167670
Step 271: 167670 + 621 = 168291
Step 272: 168291 + 621 = 168912
Step 273: 168912 + 621 = 169533
Step 274: 169533 + 621 = 170154
Step 275: 170154 + 621 = 170775
Step 276: 170775 + 621 = 171396
Step 277: 171396 + 621 = 172017
Step 278: 172017 + 621 = 172638
Step 279: 172638 + 621 = 173259
Step 280: 173259 + 621 = 173880
Step 281: 173880 + 621 = 174501
Step 282: 174501 + 621 = 175122
Step 283: 175122 + 621 = 175743
Step 284: 175743 + 621 = 176364
Step 285: 176364 + 621 = 176985
Step 286: 176985 + 621 = 177606
Step 287: 177606 + 621 = 178227
Step 288: 178227 + 621 = 178848
Step 289: 178848 + 621 = 179469
Step 290: 179469 + 621 = 180090
Step 291: 180090 + 621 = 180711
Step 292: 180711 + 621 = 181332
Step 293: 181332 + 621 = 181953
Step 294: 181953 + 621 = 182574
Step 295: 182574 + 621 = 183195
Step 296: 183195 + 621 = 183816
Step 297: 183816 + 621 = 184437
Step 298: 184437 + 621 = 185058
Step 299: 185058 + 621 = 185679
Step 300: 185679 + 621 = 186300
Step 301: 186300 + 621 = 186921
Step 302: 186921 + 621 = 187542
Step 303: 187542 + 621 = 188163
Step 304: 188163 + 621 = 188784
Step 305: 188784 + 621 = 189405
Step 306: 189405 + 621 = 190026
Step 307: 190026 + 621 = 190647
Step 308: 190647 + 621 = 191268
Step 309: 191268 + 621 = 191889
Step 310: 191889 + 621 = 192510
Step 311: 192510 + 621 = 193131
Step 312: 193131 + 621 = 193752
Step 313: 193752 + 621 = 194373
Step 314: 194373 + 621 = 194994
Step 315: 194994 + 621 = 195615
Step 316: 195615 + 621 = 196236
Step 317: 196236 + 621 = 196857
Step 318: 196857 + 621 = 197478
Step 319: 197478 + 621 = 198099
Step 320: 198099 + 621 = 198720
Step 321: 198720 + 621 = 199341
Step 322: 199341 + 621 = 199962
Step 323: 199962 + 621 = 200583
Step 324: 200583 + 621 = 201204
Step 325: 201204 + 621 = 201825
Step 326: 201825 + 621 = 202446
Step 327: 202446 + 621 = 203067
Step 328: 203067 + 621 = 203688
Step 329: 203688 + 621 = 204309
Step 330: 204309 + 621 = 204930
Step 331: 204930 + 621 = 205551
Step 332: 205551 + 621 = 206172
Step 333: 206172 + 621 = 206793
Step 334: 206793 + 621 = 207414
Step 335: 207414 + 621 = 208035
Step 336: 208035 + 621 = 208656
Step 337: 208656 + 621 = 209277
Step 338: 209277 + 621 = 209898
Step 339: 209898 + 621 = 210519
Step 340: 210519 + 621 = 211140
Step 341: 211140 + 621 = 211761
Step 342: 211761 + 621 = 212382
Step 343: 212382 + 621 = 213003
Step 344: 213003 + 621 = 213624
Step 345: 213624 + 621 = 214245
Step 346: 214245 + 621 = 214866
Step 347: 214866 + 621 = 215487
Step 348: 215487 + 621 = 216108
Step 349: 216108 + 621 = 216729
Step 350: 216729 + 621 = 217350
Step 351: 217350 + 621 = 217971
Step 352: 217971 + 621 = 218592
Step 353: 218592 + 621 = 219213
Step 354: 219213 + 621 = 219834
Step 355: 219834 + 621 = 220455
Step 356: 220455 + 621 = 221076
Step 357: 221076 + 621 = 221697
Step 358: 221697 + 621 = 222318
Step 359: 222318 + 621 = 222939
Step 360: 222939 + 621 = 223560
Step 361: 223560 + 621 = 224181
Step 362: 224181 + 621 = 224802
Step 363: 224802 + 621 = 225423
Step 364: 225423 + 621 = 226044
Step 365: 226044 + 621 = 226665
Step 366: 226665 + 621 = 227286
Step 367: 227286 + 621 = 227907
Step 368: 227907 + 621 = 228528
Step 369: 228528 + 621 = 229149
Step 370: 229149 + 621 = 229770
Step 371: 229770 + 621 = 230391
Step 372: 230391 + 621 = 231012
Step 373: 231012 + 621 = 231633
Step 374: 231633 + 621 = 232254
Step 375: 232254 + 621 = 232875
Step 376: 232875 + 621 = 233496
Step 377: 233496 + 621 = 234117
Step 378: 234117 + 621 = 234738
Step 379: 234738 + 621 = 235359
Step 380: 235359 + 621 = 235980
Step 381: 235980 + 621 = 236601
Step 382: 236601 + 621 = 237222
Step 383: 237222 + 621 = 237843
Step 384: 237843 + 621 = 238464
Step 385: 238464 + 621 = 239085
Step 386: 239085 + 621 = 239706
Step 387: 239706 + 621 = 240327
Step 388: 240327 + 621 = 240948
Step 389: 240948 + 621 = 241569
Step 390: 241569 + 621 = 242190
Step 391: 242190 + 621 = 242811
Step 392: 242811 + 621 = 243432
Step 393: 243432 + 621 = 244053
Step 394: 244053 + 621 = 244674
Step 395: 244674 + 621 = 245295
Step 396: 245295 + 621 = 245916
Step 397: 245916 + 621 = 246537
Step 398: 246537 + 621 = 247158
Step 399: 247158 + 621 = 247779
Step 400: 247779 + 621 = 248400
Step 401: 248400 + 621 = 249021
Step 402: 249021 + 621 = 249642
Step 403: 249642 + 621 = 250263
Step 404: 250263 + 621 = 250884
Step 405: 250884 + 621 = 251505
Step 406: 251505 + 621 = 252126
Step 407: 252126 + 621 = 252747
Step 408: 252747 + 621 = 253368
Step 409: 253368 + 621 = 253989
Step 410: 253989 + 621 = 254610
Step 411: 254610 + 621 = 255231
Step 412: 255231 + 621 = 255852
Step 413: 255852 + 621 = 256473
Step 414: 256473 + 621 = 257094
Step 415: 257094 + 621 = 257715
Step 416: 257715 + 621 = 258336
Step 417: 258336 + 621 = 258957
Step 418: 258957 + 621 = 259578
Step 419: 259578 + 621 = 260199
Step 420: 260199 + 621 = 260820
Step 421: 260820 + 621 = 261441
Step 422: 261441 + 621 = 262062
Step 423: 262062 + 621 = 262683
Step 424: 262683 + 621 = 263304
Step 425: 263304 + 621 = 263925
Step 426: 263925 + 621 = 264546
Step 427: 264546 + 621 = 265167
Step 428: 265167 + 621 = 265788
Step 429: 265788 + 621 = 266409
Step 430: 266409 + 621 = 267030
Step 431: 267030 + 621 = 267651
Step 432: 267651 + 621 = 268272
Step 433: 268272 + 621 = 268893
Step 434: 268893 + 621 = 269514

So, 621*434 = 269514