Alright, let's solve this math problem step by step. First, we have the number 642. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 423. So, we're going to take the number 642 and add it to itself 423 times.
Step 1: 0 + 642 = 642
Step 2: 642 + 642 = 1284
Step 3: 1284 + 642 = 1926
Step 4: 1926 + 642 = 2568
Step 5: 2568 + 642 = 3210
Step 6: 3210 + 642 = 3852
Step 7: 3852 + 642 = 4494
Step 8: 4494 + 642 = 5136
Step 9: 5136 + 642 = 5778
Step 10: 5778 + 642 = 6420
Step 11: 6420 + 642 = 7062
Step 12: 7062 + 642 = 7704
Step 13: 7704 + 642 = 8346
Step 14: 8346 + 642 = 8988
Step 15: 8988 + 642 = 9630
Step 16: 9630 + 642 = 10272
Step 17: 10272 + 642 = 10914
Step 18: 10914 + 642 = 11556
Step 19: 11556 + 642 = 12198
Step 20: 12198 + 642 = 12840
Step 21: 12840 + 642 = 13482
Step 22: 13482 + 642 = 14124
Step 23: 14124 + 642 = 14766
Step 24: 14766 + 642 = 15408
Step 25: 15408 + 642 = 16050
Step 26: 16050 + 642 = 16692
Step 27: 16692 + 642 = 17334
Step 28: 17334 + 642 = 17976
Step 29: 17976 + 642 = 18618
Step 30: 18618 + 642 = 19260
Step 31: 19260 + 642 = 19902
Step 32: 19902 + 642 = 20544
Step 33: 20544 + 642 = 21186
Step 34: 21186 + 642 = 21828
Step 35: 21828 + 642 = 22470
Step 36: 22470 + 642 = 23112
Step 37: 23112 + 642 = 23754
Step 38: 23754 + 642 = 24396
Step 39: 24396 + 642 = 25038
Step 40: 25038 + 642 = 25680
Step 41: 25680 + 642 = 26322
Step 42: 26322 + 642 = 26964
Step 43: 26964 + 642 = 27606
Step 44: 27606 + 642 = 28248
Step 45: 28248 + 642 = 28890
Step 46: 28890 + 642 = 29532
Step 47: 29532 + 642 = 30174
Step 48: 30174 + 642 = 30816
Step 49: 30816 + 642 = 31458
Step 50: 31458 + 642 = 32100
Step 51: 32100 + 642 = 32742
Step 52: 32742 + 642 = 33384
Step 53: 33384 + 642 = 34026
Step 54: 34026 + 642 = 34668
Step 55: 34668 + 642 = 35310
Step 56: 35310 + 642 = 35952
Step 57: 35952 + 642 = 36594
Step 58: 36594 + 642 = 37236
Step 59: 37236 + 642 = 37878
Step 60: 37878 + 642 = 38520
Step 61: 38520 + 642 = 39162
Step 62: 39162 + 642 = 39804
Step 63: 39804 + 642 = 40446
Step 64: 40446 + 642 = 41088
Step 65: 41088 + 642 = 41730
Step 66: 41730 + 642 = 42372
Step 67: 42372 + 642 = 43014
Step 68: 43014 + 642 = 43656
Step 69: 43656 + 642 = 44298
Step 70: 44298 + 642 = 44940
Step 71: 44940 + 642 = 45582
Step 72: 45582 + 642 = 46224
Step 73: 46224 + 642 = 46866
Step 74: 46866 + 642 = 47508
Step 75: 47508 + 642 = 48150
Step 76: 48150 + 642 = 48792
Step 77: 48792 + 642 = 49434
Step 78: 49434 + 642 = 50076
Step 79: 50076 + 642 = 50718
Step 80: 50718 + 642 = 51360
Step 81: 51360 + 642 = 52002
Step 82: 52002 + 642 = 52644
Step 83: 52644 + 642 = 53286
Step 84: 53286 + 642 = 53928
Step 85: 53928 + 642 = 54570
Step 86: 54570 + 642 = 55212
Step 87: 55212 + 642 = 55854
Step 88: 55854 + 642 = 56496
Step 89: 56496 + 642 = 57138
Step 90: 57138 + 642 = 57780
Step 91: 57780 + 642 = 58422
Step 92: 58422 + 642 = 59064
Step 93: 59064 + 642 = 59706
Step 94: 59706 + 642 = 60348
Step 95: 60348 + 642 = 60990
Step 96: 60990 + 642 = 61632
Step 97: 61632 + 642 = 62274
Step 98: 62274 + 642 = 62916
Step 99: 62916 + 642 = 63558
Step 100: 63558 + 642 = 64200
Step 101: 64200 + 642 = 64842
Step 102: 64842 + 642 = 65484
Step 103: 65484 + 642 = 66126
Step 104: 66126 + 642 = 66768
Step 105: 66768 + 642 = 67410
Step 106: 67410 + 642 = 68052
Step 107: 68052 + 642 = 68694
Step 108: 68694 + 642 = 69336
Step 109: 69336 + 642 = 69978
Step 110: 69978 + 642 = 70620
Step 111: 70620 + 642 = 71262
Step 112: 71262 + 642 = 71904
Step 113: 71904 + 642 = 72546
Step 114: 72546 + 642 = 73188
Step 115: 73188 + 642 = 73830
Step 116: 73830 + 642 = 74472
Step 117: 74472 + 642 = 75114
Step 118: 75114 + 642 = 75756
Step 119: 75756 + 642 = 76398
Step 120: 76398 + 642 = 77040
Step 121: 77040 + 642 = 77682
Step 122: 77682 + 642 = 78324
Step 123: 78324 + 642 = 78966
Step 124: 78966 + 642 = 79608
Step 125: 79608 + 642 = 80250
Step 126: 80250 + 642 = 80892
Step 127: 80892 + 642 = 81534
Step 128: 81534 + 642 = 82176
Step 129: 82176 + 642 = 82818
Step 130: 82818 + 642 = 83460
Step 131: 83460 + 642 = 84102
Step 132: 84102 + 642 = 84744
Step 133: 84744 + 642 = 85386
Step 134: 85386 + 642 = 86028
Step 135: 86028 + 642 = 86670
Step 136: 86670 + 642 = 87312
Step 137: 87312 + 642 = 87954
Step 138: 87954 + 642 = 88596
Step 139: 88596 + 642 = 89238
Step 140: 89238 + 642 = 89880
Step 141: 89880 + 642 = 90522
Step 142: 90522 + 642 = 91164
Step 143: 91164 + 642 = 91806
Step 144: 91806 + 642 = 92448
Step 145: 92448 + 642 = 93090
Step 146: 93090 + 642 = 93732
Step 147: 93732 + 642 = 94374
Step 148: 94374 + 642 = 95016
Step 149: 95016 + 642 = 95658
Step 150: 95658 + 642 = 96300
Step 151: 96300 + 642 = 96942
Step 152: 96942 + 642 = 97584
Step 153: 97584 + 642 = 98226
Step 154: 98226 + 642 = 98868
Step 155: 98868 + 642 = 99510
Step 156: 99510 + 642 = 100152
Step 157: 100152 + 642 = 100794
Step 158: 100794 + 642 = 101436
Step 159: 101436 + 642 = 102078
Step 160: 102078 + 642 = 102720
Step 161: 102720 + 642 = 103362
Step 162: 103362 + 642 = 104004
Step 163: 104004 + 642 = 104646
Step 164: 104646 + 642 = 105288
Step 165: 105288 + 642 = 105930
Step 166: 105930 + 642 = 106572
Step 167: 106572 + 642 = 107214
Step 168: 107214 + 642 = 107856
Step 169: 107856 + 642 = 108498
Step 170: 108498 + 642 = 109140
Step 171: 109140 + 642 = 109782
Step 172: 109782 + 642 = 110424
Step 173: 110424 + 642 = 111066
Step 174: 111066 + 642 = 111708
Step 175: 111708 + 642 = 112350
Step 176: 112350 + 642 = 112992
Step 177: 112992 + 642 = 113634
Step 178: 113634 + 642 = 114276
Step 179: 114276 + 642 = 114918
Step 180: 114918 + 642 = 115560
Step 181: 115560 + 642 = 116202
Step 182: 116202 + 642 = 116844
Step 183: 116844 + 642 = 117486
Step 184: 117486 + 642 = 118128
Step 185: 118128 + 642 = 118770
Step 186: 118770 + 642 = 119412
Step 187: 119412 + 642 = 120054
Step 188: 120054 + 642 = 120696
Step 189: 120696 + 642 = 121338
Step 190: 121338 + 642 = 121980
Step 191: 121980 + 642 = 122622
Step 192: 122622 + 642 = 123264
Step 193: 123264 + 642 = 123906
Step 194: 123906 + 642 = 124548
Step 195: 124548 + 642 = 125190
Step 196: 125190 + 642 = 125832
Step 197: 125832 + 642 = 126474
Step 198: 126474 + 642 = 127116
Step 199: 127116 + 642 = 127758
Step 200: 127758 + 642 = 128400
Step 201: 128400 + 642 = 129042
Step 202: 129042 + 642 = 129684
Step 203: 129684 + 642 = 130326
Step 204: 130326 + 642 = 130968
Step 205: 130968 + 642 = 131610
Step 206: 131610 + 642 = 132252
Step 207: 132252 + 642 = 132894
Step 208: 132894 + 642 = 133536
Step 209: 133536 + 642 = 134178
Step 210: 134178 + 642 = 134820
Step 211: 134820 + 642 = 135462
Step 212: 135462 + 642 = 136104
Step 213: 136104 + 642 = 136746
Step 214: 136746 + 642 = 137388
Step 215: 137388 + 642 = 138030
Step 216: 138030 + 642 = 138672
Step 217: 138672 + 642 = 139314
Step 218: 139314 + 642 = 139956
Step 219: 139956 + 642 = 140598
Step 220: 140598 + 642 = 141240
Step 221: 141240 + 642 = 141882
Step 222: 141882 + 642 = 142524
Step 223: 142524 + 642 = 143166
Step 224: 143166 + 642 = 143808
Step 225: 143808 + 642 = 144450
Step 226: 144450 + 642 = 145092
Step 227: 145092 + 642 = 145734
Step 228: 145734 + 642 = 146376
Step 229: 146376 + 642 = 147018
Step 230: 147018 + 642 = 147660
Step 231: 147660 + 642 = 148302
Step 232: 148302 + 642 = 148944
Step 233: 148944 + 642 = 149586
Step 234: 149586 + 642 = 150228
Step 235: 150228 + 642 = 150870
Step 236: 150870 + 642 = 151512
Step 237: 151512 + 642 = 152154
Step 238: 152154 + 642 = 152796
Step 239: 152796 + 642 = 153438
Step 240: 153438 + 642 = 154080
Step 241: 154080 + 642 = 154722
Step 242: 154722 + 642 = 155364
Step 243: 155364 + 642 = 156006
Step 244: 156006 + 642 = 156648
Step 245: 156648 + 642 = 157290
Step 246: 157290 + 642 = 157932
Step 247: 157932 + 642 = 158574
Step 248: 158574 + 642 = 159216
Step 249: 159216 + 642 = 159858
Step 250: 159858 + 642 = 160500
Step 251: 160500 + 642 = 161142
Step 252: 161142 + 642 = 161784
Step 253: 161784 + 642 = 162426
Step 254: 162426 + 642 = 163068
Step 255: 163068 + 642 = 163710
Step 256: 163710 + 642 = 164352
Step 257: 164352 + 642 = 164994
Step 258: 164994 + 642 = 165636
Step 259: 165636 + 642 = 166278
Step 260: 166278 + 642 = 166920
Step 261: 166920 + 642 = 167562
Step 262: 167562 + 642 = 168204
Step 263: 168204 + 642 = 168846
Step 264: 168846 + 642 = 169488
Step 265: 169488 + 642 = 170130
Step 266: 170130 + 642 = 170772
Step 267: 170772 + 642 = 171414
Step 268: 171414 + 642 = 172056
Step 269: 172056 + 642 = 172698
Step 270: 172698 + 642 = 173340
Step 271: 173340 + 642 = 173982
Step 272: 173982 + 642 = 174624
Step 273: 174624 + 642 = 175266
Step 274: 175266 + 642 = 175908
Step 275: 175908 + 642 = 176550
Step 276: 176550 + 642 = 177192
Step 277: 177192 + 642 = 177834
Step 278: 177834 + 642 = 178476
Step 279: 178476 + 642 = 179118
Step 280: 179118 + 642 = 179760
Step 281: 179760 + 642 = 180402
Step 282: 180402 + 642 = 181044
Step 283: 181044 + 642 = 181686
Step 284: 181686 + 642 = 182328
Step 285: 182328 + 642 = 182970
Step 286: 182970 + 642 = 183612
Step 287: 183612 + 642 = 184254
Step 288: 184254 + 642 = 184896
Step 289: 184896 + 642 = 185538
Step 290: 185538 + 642 = 186180
Step 291: 186180 + 642 = 186822
Step 292: 186822 + 642 = 187464
Step 293: 187464 + 642 = 188106
Step 294: 188106 + 642 = 188748
Step 295: 188748 + 642 = 189390
Step 296: 189390 + 642 = 190032
Step 297: 190032 + 642 = 190674
Step 298: 190674 + 642 = 191316
Step 299: 191316 + 642 = 191958
Step 300: 191958 + 642 = 192600
Step 301: 192600 + 642 = 193242
Step 302: 193242 + 642 = 193884
Step 303: 193884 + 642 = 194526
Step 304: 194526 + 642 = 195168
Step 305: 195168 + 642 = 195810
Step 306: 195810 + 642 = 196452
Step 307: 196452 + 642 = 197094
Step 308: 197094 + 642 = 197736
Step 309: 197736 + 642 = 198378
Step 310: 198378 + 642 = 199020
Step 311: 199020 + 642 = 199662
Step 312: 199662 + 642 = 200304
Step 313: 200304 + 642 = 200946
Step 314: 200946 + 642 = 201588
Step 315: 201588 + 642 = 202230
Step 316: 202230 + 642 = 202872
Step 317: 202872 + 642 = 203514
Step 318: 203514 + 642 = 204156
Step 319: 204156 + 642 = 204798
Step 320: 204798 + 642 = 205440
Step 321: 205440 + 642 = 206082
Step 322: 206082 + 642 = 206724
Step 323: 206724 + 642 = 207366
Step 324: 207366 + 642 = 208008
Step 325: 208008 + 642 = 208650
Step 326: 208650 + 642 = 209292
Step 327: 209292 + 642 = 209934
Step 328: 209934 + 642 = 210576
Step 329: 210576 + 642 = 211218
Step 330: 211218 + 642 = 211860
Step 331: 211860 + 642 = 212502
Step 332: 212502 + 642 = 213144
Step 333: 213144 + 642 = 213786
Step 334: 213786 + 642 = 214428
Step 335: 214428 + 642 = 215070
Step 336: 215070 + 642 = 215712
Step 337: 215712 + 642 = 216354
Step 338: 216354 + 642 = 216996
Step 339: 216996 + 642 = 217638
Step 340: 217638 + 642 = 218280
Step 341: 218280 + 642 = 218922
Step 342: 218922 + 642 = 219564
Step 343: 219564 + 642 = 220206
Step 344: 220206 + 642 = 220848
Step 345: 220848 + 642 = 221490
Step 346: 221490 + 642 = 222132
Step 347: 222132 + 642 = 222774
Step 348: 222774 + 642 = 223416
Step 349: 223416 + 642 = 224058
Step 350: 224058 + 642 = 224700
Step 351: 224700 + 642 = 225342
Step 352: 225342 + 642 = 225984
Step 353: 225984 + 642 = 226626
Step 354: 226626 + 642 = 227268
Step 355: 227268 + 642 = 227910
Step 356: 227910 + 642 = 228552
Step 357: 228552 + 642 = 229194
Step 358: 229194 + 642 = 229836
Step 359: 229836 + 642 = 230478
Step 360: 230478 + 642 = 231120
Step 361: 231120 + 642 = 231762
Step 362: 231762 + 642 = 232404
Step 363: 232404 + 642 = 233046
Step 364: 233046 + 642 = 233688
Step 365: 233688 + 642 = 234330
Step 366: 234330 + 642 = 234972
Step 367: 234972 + 642 = 235614
Step 368: 235614 + 642 = 236256
Step 369: 236256 + 642 = 236898
Step 370: 236898 + 642 = 237540
Step 371: 237540 + 642 = 238182
Step 372: 238182 + 642 = 238824
Step 373: 238824 + 642 = 239466
Step 374: 239466 + 642 = 240108
Step 375: 240108 + 642 = 240750
Step 376: 240750 + 642 = 241392
Step 377: 241392 + 642 = 242034
Step 378: 242034 + 642 = 242676
Step 379: 242676 + 642 = 243318
Step 380: 243318 + 642 = 243960
Step 381: 243960 + 642 = 244602
Step 382: 244602 + 642 = 245244
Step 383: 245244 + 642 = 245886
Step 384: 245886 + 642 = 246528
Step 385: 246528 + 642 = 247170
Step 386: 247170 + 642 = 247812
Step 387: 247812 + 642 = 248454
Step 388: 248454 + 642 = 249096
Step 389: 249096 + 642 = 249738
Step 390: 249738 + 642 = 250380
Step 391: 250380 + 642 = 251022
Step 392: 251022 + 642 = 251664
Step 393: 251664 + 642 = 252306
Step 394: 252306 + 642 = 252948
Step 395: 252948 + 642 = 253590
Step 396: 253590 + 642 = 254232
Step 397: 254232 + 642 = 254874
Step 398: 254874 + 642 = 255516
Step 399: 255516 + 642 = 256158
Step 400: 256158 + 642 = 256800
Step 401: 256800 + 642 = 257442
Step 402: 257442 + 642 = 258084
Step 403: 258084 + 642 = 258726
Step 404: 258726 + 642 = 259368
Step 405: 259368 + 642 = 260010
Step 406: 260010 + 642 = 260652
Step 407: 260652 + 642 = 261294
Step 408: 261294 + 642 = 261936
Step 409: 261936 + 642 = 262578
Step 410: 262578 + 642 = 263220
Step 411: 263220 + 642 = 263862
Step 412: 263862 + 642 = 264504
Step 413: 264504 + 642 = 265146
Step 414: 265146 + 642 = 265788
Step 415: 265788 + 642 = 266430
Step 416: 266430 + 642 = 267072
Step 417: 267072 + 642 = 267714
Step 418: 267714 + 642 = 268356
Step 419: 268356 + 642 = 268998
Step 420: 268998 + 642 = 269640
Step 421: 269640 + 642 = 270282
Step 422: 270282 + 642 = 270924
Step 423: 270924 + 642 = 271566

So, 642*423 = 271566