OK, let's work through this together. We're starting with 641 and we're going to multiply it by 434, which means we add 641 to itself 434 times.
Step 1: 0 + 641 = 641
Step 2: 641 + 641 = 1282
Step 3: 1282 + 641 = 1923
Step 4: 1923 + 641 = 2564
Step 5: 2564 + 641 = 3205
Step 6: 3205 + 641 = 3846
Step 7: 3846 + 641 = 4487
Step 8: 4487 + 641 = 5128
Step 9: 5128 + 641 = 5769
Step 10: 5769 + 641 = 6410
Step 11: 6410 + 641 = 7051
Step 12: 7051 + 641 = 7692
Step 13: 7692 + 641 = 8333
Step 14: 8333 + 641 = 8974
Step 15: 8974 + 641 = 9615
Step 16: 9615 + 641 = 10256
Step 17: 10256 + 641 = 10897
Step 18: 10897 + 641 = 11538
Step 19: 11538 + 641 = 12179
Step 20: 12179 + 641 = 12820
Step 21: 12820 + 641 = 13461
Step 22: 13461 + 641 = 14102
Step 23: 14102 + 641 = 14743
Step 24: 14743 + 641 = 15384
Step 25: 15384 + 641 = 16025
Step 26: 16025 + 641 = 16666
Step 27: 16666 + 641 = 17307
Step 28: 17307 + 641 = 17948
Step 29: 17948 + 641 = 18589
Step 30: 18589 + 641 = 19230
Step 31: 19230 + 641 = 19871
Step 32: 19871 + 641 = 20512
Step 33: 20512 + 641 = 21153
Step 34: 21153 + 641 = 21794
Step 35: 21794 + 641 = 22435
Step 36: 22435 + 641 = 23076
Step 37: 23076 + 641 = 23717
Step 38: 23717 + 641 = 24358
Step 39: 24358 + 641 = 24999
Step 40: 24999 + 641 = 25640
Step 41: 25640 + 641 = 26281
Step 42: 26281 + 641 = 26922
Step 43: 26922 + 641 = 27563
Step 44: 27563 + 641 = 28204
Step 45: 28204 + 641 = 28845
Step 46: 28845 + 641 = 29486
Step 47: 29486 + 641 = 30127
Step 48: 30127 + 641 = 30768
Step 49: 30768 + 641 = 31409
Step 50: 31409 + 641 = 32050
Step 51: 32050 + 641 = 32691
Step 52: 32691 + 641 = 33332
Step 53: 33332 + 641 = 33973
Step 54: 33973 + 641 = 34614
Step 55: 34614 + 641 = 35255
Step 56: 35255 + 641 = 35896
Step 57: 35896 + 641 = 36537
Step 58: 36537 + 641 = 37178
Step 59: 37178 + 641 = 37819
Step 60: 37819 + 641 = 38460
Step 61: 38460 + 641 = 39101
Step 62: 39101 + 641 = 39742
Step 63: 39742 + 641 = 40383
Step 64: 40383 + 641 = 41024
Step 65: 41024 + 641 = 41665
Step 66: 41665 + 641 = 42306
Step 67: 42306 + 641 = 42947
Step 68: 42947 + 641 = 43588
Step 69: 43588 + 641 = 44229
Step 70: 44229 + 641 = 44870
Step 71: 44870 + 641 = 45511
Step 72: 45511 + 641 = 46152
Step 73: 46152 + 641 = 46793
Step 74: 46793 + 641 = 47434
Step 75: 47434 + 641 = 48075
Step 76: 48075 + 641 = 48716
Step 77: 48716 + 641 = 49357
Step 78: 49357 + 641 = 49998
Step 79: 49998 + 641 = 50639
Step 80: 50639 + 641 = 51280
Step 81: 51280 + 641 = 51921
Step 82: 51921 + 641 = 52562
Step 83: 52562 + 641 = 53203
Step 84: 53203 + 641 = 53844
Step 85: 53844 + 641 = 54485
Step 86: 54485 + 641 = 55126
Step 87: 55126 + 641 = 55767
Step 88: 55767 + 641 = 56408
Step 89: 56408 + 641 = 57049
Step 90: 57049 + 641 = 57690
Step 91: 57690 + 641 = 58331
Step 92: 58331 + 641 = 58972
Step 93: 58972 + 641 = 59613
Step 94: 59613 + 641 = 60254
Step 95: 60254 + 641 = 60895
Step 96: 60895 + 641 = 61536
Step 97: 61536 + 641 = 62177
Step 98: 62177 + 641 = 62818
Step 99: 62818 + 641 = 63459
Step 100: 63459 + 641 = 64100
Step 101: 64100 + 641 = 64741
Step 102: 64741 + 641 = 65382
Step 103: 65382 + 641 = 66023
Step 104: 66023 + 641 = 66664
Step 105: 66664 + 641 = 67305
Step 106: 67305 + 641 = 67946
Step 107: 67946 + 641 = 68587
Step 108: 68587 + 641 = 69228
Step 109: 69228 + 641 = 69869
Step 110: 69869 + 641 = 70510
Step 111: 70510 + 641 = 71151
Step 112: 71151 + 641 = 71792
Step 113: 71792 + 641 = 72433
Step 114: 72433 + 641 = 73074
Step 115: 73074 + 641 = 73715
Step 116: 73715 + 641 = 74356
Step 117: 74356 + 641 = 74997
Step 118: 74997 + 641 = 75638
Step 119: 75638 + 641 = 76279
Step 120: 76279 + 641 = 76920
Step 121: 76920 + 641 = 77561
Step 122: 77561 + 641 = 78202
Step 123: 78202 + 641 = 78843
Step 124: 78843 + 641 = 79484
Step 125: 79484 + 641 = 80125
Step 126: 80125 + 641 = 80766
Step 127: 80766 + 641 = 81407
Step 128: 81407 + 641 = 82048
Step 129: 82048 + 641 = 82689
Step 130: 82689 + 641 = 83330
Step 131: 83330 + 641 = 83971
Step 132: 83971 + 641 = 84612
Step 133: 84612 + 641 = 85253
Step 134: 85253 + 641 = 85894
Step 135: 85894 + 641 = 86535
Step 136: 86535 + 641 = 87176
Step 137: 87176 + 641 = 87817
Step 138: 87817 + 641 = 88458
Step 139: 88458 + 641 = 89099
Step 140: 89099 + 641 = 89740
Step 141: 89740 + 641 = 90381
Step 142: 90381 + 641 = 91022
Step 143: 91022 + 641 = 91663
Step 144: 91663 + 641 = 92304
Step 145: 92304 + 641 = 92945
Step 146: 92945 + 641 = 93586
Step 147: 93586 + 641 = 94227
Step 148: 94227 + 641 = 94868
Step 149: 94868 + 641 = 95509
Step 150: 95509 + 641 = 96150
Step 151: 96150 + 641 = 96791
Step 152: 96791 + 641 = 97432
Step 153: 97432 + 641 = 98073
Step 154: 98073 + 641 = 98714
Step 155: 98714 + 641 = 99355
Step 156: 99355 + 641 = 99996
Step 157: 99996 + 641 = 100637
Step 158: 100637 + 641 = 101278
Step 159: 101278 + 641 = 101919
Step 160: 101919 + 641 = 102560
Step 161: 102560 + 641 = 103201
Step 162: 103201 + 641 = 103842
Step 163: 103842 + 641 = 104483
Step 164: 104483 + 641 = 105124
Step 165: 105124 + 641 = 105765
Step 166: 105765 + 641 = 106406
Step 167: 106406 + 641 = 107047
Step 168: 107047 + 641 = 107688
Step 169: 107688 + 641 = 108329
Step 170: 108329 + 641 = 108970
Step 171: 108970 + 641 = 109611
Step 172: 109611 + 641 = 110252
Step 173: 110252 + 641 = 110893
Step 174: 110893 + 641 = 111534
Step 175: 111534 + 641 = 112175
Step 176: 112175 + 641 = 112816
Step 177: 112816 + 641 = 113457
Step 178: 113457 + 641 = 114098
Step 179: 114098 + 641 = 114739
Step 180: 114739 + 641 = 115380
Step 181: 115380 + 641 = 116021
Step 182: 116021 + 641 = 116662
Step 183: 116662 + 641 = 117303
Step 184: 117303 + 641 = 117944
Step 185: 117944 + 641 = 118585
Step 186: 118585 + 641 = 119226
Step 187: 119226 + 641 = 119867
Step 188: 119867 + 641 = 120508
Step 189: 120508 + 641 = 121149
Step 190: 121149 + 641 = 121790
Step 191: 121790 + 641 = 122431
Step 192: 122431 + 641 = 123072
Step 193: 123072 + 641 = 123713
Step 194: 123713 + 641 = 124354
Step 195: 124354 + 641 = 124995
Step 196: 124995 + 641 = 125636
Step 197: 125636 + 641 = 126277
Step 198: 126277 + 641 = 126918
Step 199: 126918 + 641 = 127559
Step 200: 127559 + 641 = 128200
Step 201: 128200 + 641 = 128841
Step 202: 128841 + 641 = 129482
Step 203: 129482 + 641 = 130123
Step 204: 130123 + 641 = 130764
Step 205: 130764 + 641 = 131405
Step 206: 131405 + 641 = 132046
Step 207: 132046 + 641 = 132687
Step 208: 132687 + 641 = 133328
Step 209: 133328 + 641 = 133969
Step 210: 133969 + 641 = 134610
Step 211: 134610 + 641 = 135251
Step 212: 135251 + 641 = 135892
Step 213: 135892 + 641 = 136533
Step 214: 136533 + 641 = 137174
Step 215: 137174 + 641 = 137815
Step 216: 137815 + 641 = 138456
Step 217: 138456 + 641 = 139097
Step 218: 139097 + 641 = 139738
Step 219: 139738 + 641 = 140379
Step 220: 140379 + 641 = 141020
Step 221: 141020 + 641 = 141661
Step 222: 141661 + 641 = 142302
Step 223: 142302 + 641 = 142943
Step 224: 142943 + 641 = 143584
Step 225: 143584 + 641 = 144225
Step 226: 144225 + 641 = 144866
Step 227: 144866 + 641 = 145507
Step 228: 145507 + 641 = 146148
Step 229: 146148 + 641 = 146789
Step 230: 146789 + 641 = 147430
Step 231: 147430 + 641 = 148071
Step 232: 148071 + 641 = 148712
Step 233: 148712 + 641 = 149353
Step 234: 149353 + 641 = 149994
Step 235: 149994 + 641 = 150635
Step 236: 150635 + 641 = 151276
Step 237: 151276 + 641 = 151917
Step 238: 151917 + 641 = 152558
Step 239: 152558 + 641 = 153199
Step 240: 153199 + 641 = 153840
Step 241: 153840 + 641 = 154481
Step 242: 154481 + 641 = 155122
Step 243: 155122 + 641 = 155763
Step 244: 155763 + 641 = 156404
Step 245: 156404 + 641 = 157045
Step 246: 157045 + 641 = 157686
Step 247: 157686 + 641 = 158327
Step 248: 158327 + 641 = 158968
Step 249: 158968 + 641 = 159609
Step 250: 159609 + 641 = 160250
Step 251: 160250 + 641 = 160891
Step 252: 160891 + 641 = 161532
Step 253: 161532 + 641 = 162173
Step 254: 162173 + 641 = 162814
Step 255: 162814 + 641 = 163455
Step 256: 163455 + 641 = 164096
Step 257: 164096 + 641 = 164737
Step 258: 164737 + 641 = 165378
Step 259: 165378 + 641 = 166019
Step 260: 166019 + 641 = 166660
Step 261: 166660 + 641 = 167301
Step 262: 167301 + 641 = 167942
Step 263: 167942 + 641 = 168583
Step 264: 168583 + 641 = 169224
Step 265: 169224 + 641 = 169865
Step 266: 169865 + 641 = 170506
Step 267: 170506 + 641 = 171147
Step 268: 171147 + 641 = 171788
Step 269: 171788 + 641 = 172429
Step 270: 172429 + 641 = 173070
Step 271: 173070 + 641 = 173711
Step 272: 173711 + 641 = 174352
Step 273: 174352 + 641 = 174993
Step 274: 174993 + 641 = 175634
Step 275: 175634 + 641 = 176275
Step 276: 176275 + 641 = 176916
Step 277: 176916 + 641 = 177557
Step 278: 177557 + 641 = 178198
Step 279: 178198 + 641 = 178839
Step 280: 178839 + 641 = 179480
Step 281: 179480 + 641 = 180121
Step 282: 180121 + 641 = 180762
Step 283: 180762 + 641 = 181403
Step 284: 181403 + 641 = 182044
Step 285: 182044 + 641 = 182685
Step 286: 182685 + 641 = 183326
Step 287: 183326 + 641 = 183967
Step 288: 183967 + 641 = 184608
Step 289: 184608 + 641 = 185249
Step 290: 185249 + 641 = 185890
Step 291: 185890 + 641 = 186531
Step 292: 186531 + 641 = 187172
Step 293: 187172 + 641 = 187813
Step 294: 187813 + 641 = 188454
Step 295: 188454 + 641 = 189095
Step 296: 189095 + 641 = 189736
Step 297: 189736 + 641 = 190377
Step 298: 190377 + 641 = 191018
Step 299: 191018 + 641 = 191659
Step 300: 191659 + 641 = 192300
Step 301: 192300 + 641 = 192941
Step 302: 192941 + 641 = 193582
Step 303: 193582 + 641 = 194223
Step 304: 194223 + 641 = 194864
Step 305: 194864 + 641 = 195505
Step 306: 195505 + 641 = 196146
Step 307: 196146 + 641 = 196787
Step 308: 196787 + 641 = 197428
Step 309: 197428 + 641 = 198069
Step 310: 198069 + 641 = 198710
Step 311: 198710 + 641 = 199351
Step 312: 199351 + 641 = 199992
Step 313: 199992 + 641 = 200633
Step 314: 200633 + 641 = 201274
Step 315: 201274 + 641 = 201915
Step 316: 201915 + 641 = 202556
Step 317: 202556 + 641 = 203197
Step 318: 203197 + 641 = 203838
Step 319: 203838 + 641 = 204479
Step 320: 204479 + 641 = 205120
Step 321: 205120 + 641 = 205761
Step 322: 205761 + 641 = 206402
Step 323: 206402 + 641 = 207043
Step 324: 207043 + 641 = 207684
Step 325: 207684 + 641 = 208325
Step 326: 208325 + 641 = 208966
Step 327: 208966 + 641 = 209607
Step 328: 209607 + 641 = 210248
Step 329: 210248 + 641 = 210889
Step 330: 210889 + 641 = 211530
Step 331: 211530 + 641 = 212171
Step 332: 212171 + 641 = 212812
Step 333: 212812 + 641 = 213453
Step 334: 213453 + 641 = 214094
Step 335: 214094 + 641 = 214735
Step 336: 214735 + 641 = 215376
Step 337: 215376 + 641 = 216017
Step 338: 216017 + 641 = 216658
Step 339: 216658 + 641 = 217299
Step 340: 217299 + 641 = 217940
Step 341: 217940 + 641 = 218581
Step 342: 218581 + 641 = 219222
Step 343: 219222 + 641 = 219863
Step 344: 219863 + 641 = 220504
Step 345: 220504 + 641 = 221145
Step 346: 221145 + 641 = 221786
Step 347: 221786 + 641 = 222427
Step 348: 222427 + 641 = 223068
Step 349: 223068 + 641 = 223709
Step 350: 223709 + 641 = 224350
Step 351: 224350 + 641 = 224991
Step 352: 224991 + 641 = 225632
Step 353: 225632 + 641 = 226273
Step 354: 226273 + 641 = 226914
Step 355: 226914 + 641 = 227555
Step 356: 227555 + 641 = 228196
Step 357: 228196 + 641 = 228837
Step 358: 228837 + 641 = 229478
Step 359: 229478 + 641 = 230119
Step 360: 230119 + 641 = 230760
Step 361: 230760 + 641 = 231401
Step 362: 231401 + 641 = 232042
Step 363: 232042 + 641 = 232683
Step 364: 232683 + 641 = 233324
Step 365: 233324 + 641 = 233965
Step 366: 233965 + 641 = 234606
Step 367: 234606 + 641 = 235247
Step 368: 235247 + 641 = 235888
Step 369: 235888 + 641 = 236529
Step 370: 236529 + 641 = 237170
Step 371: 237170 + 641 = 237811
Step 372: 237811 + 641 = 238452
Step 373: 238452 + 641 = 239093
Step 374: 239093 + 641 = 239734
Step 375: 239734 + 641 = 240375
Step 376: 240375 + 641 = 241016
Step 377: 241016 + 641 = 241657
Step 378: 241657 + 641 = 242298
Step 379: 242298 + 641 = 242939
Step 380: 242939 + 641 = 243580
Step 381: 243580 + 641 = 244221
Step 382: 244221 + 641 = 244862
Step 383: 244862 + 641 = 245503
Step 384: 245503 + 641 = 246144
Step 385: 246144 + 641 = 246785
Step 386: 246785 + 641 = 247426
Step 387: 247426 + 641 = 248067
Step 388: 248067 + 641 = 248708
Step 389: 248708 + 641 = 249349
Step 390: 249349 + 641 = 249990
Step 391: 249990 + 641 = 250631
Step 392: 250631 + 641 = 251272
Step 393: 251272 + 641 = 251913
Step 394: 251913 + 641 = 252554
Step 395: 252554 + 641 = 253195
Step 396: 253195 + 641 = 253836
Step 397: 253836 + 641 = 254477
Step 398: 254477 + 641 = 255118
Step 399: 255118 + 641 = 255759
Step 400: 255759 + 641 = 256400
Step 401: 256400 + 641 = 257041
Step 402: 257041 + 641 = 257682
Step 403: 257682 + 641 = 258323
Step 404: 258323 + 641 = 258964
Step 405: 258964 + 641 = 259605
Step 406: 259605 + 641 = 260246
Step 407: 260246 + 641 = 260887
Step 408: 260887 + 641 = 261528
Step 409: 261528 + 641 = 262169
Step 410: 262169 + 641 = 262810
Step 411: 262810 + 641 = 263451
Step 412: 263451 + 641 = 264092
Step 413: 264092 + 641 = 264733
Step 414: 264733 + 641 = 265374
Step 415: 265374 + 641 = 266015
Step 416: 266015 + 641 = 266656
Step 417: 266656 + 641 = 267297
Step 418: 267297 + 641 = 267938
Step 419: 267938 + 641 = 268579
Step 420: 268579 + 641 = 269220
Step 421: 269220 + 641 = 269861
Step 422: 269861 + 641 = 270502
Step 423: 270502 + 641 = 271143
Step 424: 271143 + 641 = 271784
Step 425: 271784 + 641 = 272425
Step 426: 272425 + 641 = 273066
Step 427: 273066 + 641 = 273707
Step 428: 273707 + 641 = 274348
Step 429: 274348 + 641 = 274989
Step 430: 274989 + 641 = 275630
Step 431: 275630 + 641 = 276271
Step 432: 276271 + 641 = 276912
Step 433: 276912 + 641 = 277553
Step 434: 277553 + 641 = 278194

So, 641*434 = 278194