OK, let's crack this. We're given 638 and our task is to multiply it by 413. Essentially, we'll be adding 638 to itself 413 times.
Step 1: 0 + 638 = 638
Step 2: 638 + 638 = 1276
Step 3: 1276 + 638 = 1914
Step 4: 1914 + 638 = 2552
Step 5: 2552 + 638 = 3190
Step 6: 3190 + 638 = 3828
Step 7: 3828 + 638 = 4466
Step 8: 4466 + 638 = 5104
Step 9: 5104 + 638 = 5742
Step 10: 5742 + 638 = 6380
Step 11: 6380 + 638 = 7018
Step 12: 7018 + 638 = 7656
Step 13: 7656 + 638 = 8294
Step 14: 8294 + 638 = 8932
Step 15: 8932 + 638 = 9570
Step 16: 9570 + 638 = 10208
Step 17: 10208 + 638 = 10846
Step 18: 10846 + 638 = 11484
Step 19: 11484 + 638 = 12122
Step 20: 12122 + 638 = 12760
Step 21: 12760 + 638 = 13398
Step 22: 13398 + 638 = 14036
Step 23: 14036 + 638 = 14674
Step 24: 14674 + 638 = 15312
Step 25: 15312 + 638 = 15950
Step 26: 15950 + 638 = 16588
Step 27: 16588 + 638 = 17226
Step 28: 17226 + 638 = 17864
Step 29: 17864 + 638 = 18502
Step 30: 18502 + 638 = 19140
Step 31: 19140 + 638 = 19778
Step 32: 19778 + 638 = 20416
Step 33: 20416 + 638 = 21054
Step 34: 21054 + 638 = 21692
Step 35: 21692 + 638 = 22330
Step 36: 22330 + 638 = 22968
Step 37: 22968 + 638 = 23606
Step 38: 23606 + 638 = 24244
Step 39: 24244 + 638 = 24882
Step 40: 24882 + 638 = 25520
Step 41: 25520 + 638 = 26158
Step 42: 26158 + 638 = 26796
Step 43: 26796 + 638 = 27434
Step 44: 27434 + 638 = 28072
Step 45: 28072 + 638 = 28710
Step 46: 28710 + 638 = 29348
Step 47: 29348 + 638 = 29986
Step 48: 29986 + 638 = 30624
Step 49: 30624 + 638 = 31262
Step 50: 31262 + 638 = 31900
Step 51: 31900 + 638 = 32538
Step 52: 32538 + 638 = 33176
Step 53: 33176 + 638 = 33814
Step 54: 33814 + 638 = 34452
Step 55: 34452 + 638 = 35090
Step 56: 35090 + 638 = 35728
Step 57: 35728 + 638 = 36366
Step 58: 36366 + 638 = 37004
Step 59: 37004 + 638 = 37642
Step 60: 37642 + 638 = 38280
Step 61: 38280 + 638 = 38918
Step 62: 38918 + 638 = 39556
Step 63: 39556 + 638 = 40194
Step 64: 40194 + 638 = 40832
Step 65: 40832 + 638 = 41470
Step 66: 41470 + 638 = 42108
Step 67: 42108 + 638 = 42746
Step 68: 42746 + 638 = 43384
Step 69: 43384 + 638 = 44022
Step 70: 44022 + 638 = 44660
Step 71: 44660 + 638 = 45298
Step 72: 45298 + 638 = 45936
Step 73: 45936 + 638 = 46574
Step 74: 46574 + 638 = 47212
Step 75: 47212 + 638 = 47850
Step 76: 47850 + 638 = 48488
Step 77: 48488 + 638 = 49126
Step 78: 49126 + 638 = 49764
Step 79: 49764 + 638 = 50402
Step 80: 50402 + 638 = 51040
Step 81: 51040 + 638 = 51678
Step 82: 51678 + 638 = 52316
Step 83: 52316 + 638 = 52954
Step 84: 52954 + 638 = 53592
Step 85: 53592 + 638 = 54230
Step 86: 54230 + 638 = 54868
Step 87: 54868 + 638 = 55506
Step 88: 55506 + 638 = 56144
Step 89: 56144 + 638 = 56782
Step 90: 56782 + 638 = 57420
Step 91: 57420 + 638 = 58058
Step 92: 58058 + 638 = 58696
Step 93: 58696 + 638 = 59334
Step 94: 59334 + 638 = 59972
Step 95: 59972 + 638 = 60610
Step 96: 60610 + 638 = 61248
Step 97: 61248 + 638 = 61886
Step 98: 61886 + 638 = 62524
Step 99: 62524 + 638 = 63162
Step 100: 63162 + 638 = 63800
Step 101: 63800 + 638 = 64438
Step 102: 64438 + 638 = 65076
Step 103: 65076 + 638 = 65714
Step 104: 65714 + 638 = 66352
Step 105: 66352 + 638 = 66990
Step 106: 66990 + 638 = 67628
Step 107: 67628 + 638 = 68266
Step 108: 68266 + 638 = 68904
Step 109: 68904 + 638 = 69542
Step 110: 69542 + 638 = 70180
Step 111: 70180 + 638 = 70818
Step 112: 70818 + 638 = 71456
Step 113: 71456 + 638 = 72094
Step 114: 72094 + 638 = 72732
Step 115: 72732 + 638 = 73370
Step 116: 73370 + 638 = 74008
Step 117: 74008 + 638 = 74646
Step 118: 74646 + 638 = 75284
Step 119: 75284 + 638 = 75922
Step 120: 75922 + 638 = 76560
Step 121: 76560 + 638 = 77198
Step 122: 77198 + 638 = 77836
Step 123: 77836 + 638 = 78474
Step 124: 78474 + 638 = 79112
Step 125: 79112 + 638 = 79750
Step 126: 79750 + 638 = 80388
Step 127: 80388 + 638 = 81026
Step 128: 81026 + 638 = 81664
Step 129: 81664 + 638 = 82302
Step 130: 82302 + 638 = 82940
Step 131: 82940 + 638 = 83578
Step 132: 83578 + 638 = 84216
Step 133: 84216 + 638 = 84854
Step 134: 84854 + 638 = 85492
Step 135: 85492 + 638 = 86130
Step 136: 86130 + 638 = 86768
Step 137: 86768 + 638 = 87406
Step 138: 87406 + 638 = 88044
Step 139: 88044 + 638 = 88682
Step 140: 88682 + 638 = 89320
Step 141: 89320 + 638 = 89958
Step 142: 89958 + 638 = 90596
Step 143: 90596 + 638 = 91234
Step 144: 91234 + 638 = 91872
Step 145: 91872 + 638 = 92510
Step 146: 92510 + 638 = 93148
Step 147: 93148 + 638 = 93786
Step 148: 93786 + 638 = 94424
Step 149: 94424 + 638 = 95062
Step 150: 95062 + 638 = 95700
Step 151: 95700 + 638 = 96338
Step 152: 96338 + 638 = 96976
Step 153: 96976 + 638 = 97614
Step 154: 97614 + 638 = 98252
Step 155: 98252 + 638 = 98890
Step 156: 98890 + 638 = 99528
Step 157: 99528 + 638 = 100166
Step 158: 100166 + 638 = 100804
Step 159: 100804 + 638 = 101442
Step 160: 101442 + 638 = 102080
Step 161: 102080 + 638 = 102718
Step 162: 102718 + 638 = 103356
Step 163: 103356 + 638 = 103994
Step 164: 103994 + 638 = 104632
Step 165: 104632 + 638 = 105270
Step 166: 105270 + 638 = 105908
Step 167: 105908 + 638 = 106546
Step 168: 106546 + 638 = 107184
Step 169: 107184 + 638 = 107822
Step 170: 107822 + 638 = 108460
Step 171: 108460 + 638 = 109098
Step 172: 109098 + 638 = 109736
Step 173: 109736 + 638 = 110374
Step 174: 110374 + 638 = 111012
Step 175: 111012 + 638 = 111650
Step 176: 111650 + 638 = 112288
Step 177: 112288 + 638 = 112926
Step 178: 112926 + 638 = 113564
Step 179: 113564 + 638 = 114202
Step 180: 114202 + 638 = 114840
Step 181: 114840 + 638 = 115478
Step 182: 115478 + 638 = 116116
Step 183: 116116 + 638 = 116754
Step 184: 116754 + 638 = 117392
Step 185: 117392 + 638 = 118030
Step 186: 118030 + 638 = 118668
Step 187: 118668 + 638 = 119306
Step 188: 119306 + 638 = 119944
Step 189: 119944 + 638 = 120582
Step 190: 120582 + 638 = 121220
Step 191: 121220 + 638 = 121858
Step 192: 121858 + 638 = 122496
Step 193: 122496 + 638 = 123134
Step 194: 123134 + 638 = 123772
Step 195: 123772 + 638 = 124410
Step 196: 124410 + 638 = 125048
Step 197: 125048 + 638 = 125686
Step 198: 125686 + 638 = 126324
Step 199: 126324 + 638 = 126962
Step 200: 126962 + 638 = 127600
Step 201: 127600 + 638 = 128238
Step 202: 128238 + 638 = 128876
Step 203: 128876 + 638 = 129514
Step 204: 129514 + 638 = 130152
Step 205: 130152 + 638 = 130790
Step 206: 130790 + 638 = 131428
Step 207: 131428 + 638 = 132066
Step 208: 132066 + 638 = 132704
Step 209: 132704 + 638 = 133342
Step 210: 133342 + 638 = 133980
Step 211: 133980 + 638 = 134618
Step 212: 134618 + 638 = 135256
Step 213: 135256 + 638 = 135894
Step 214: 135894 + 638 = 136532
Step 215: 136532 + 638 = 137170
Step 216: 137170 + 638 = 137808
Step 217: 137808 + 638 = 138446
Step 218: 138446 + 638 = 139084
Step 219: 139084 + 638 = 139722
Step 220: 139722 + 638 = 140360
Step 221: 140360 + 638 = 140998
Step 222: 140998 + 638 = 141636
Step 223: 141636 + 638 = 142274
Step 224: 142274 + 638 = 142912
Step 225: 142912 + 638 = 143550
Step 226: 143550 + 638 = 144188
Step 227: 144188 + 638 = 144826
Step 228: 144826 + 638 = 145464
Step 229: 145464 + 638 = 146102
Step 230: 146102 + 638 = 146740
Step 231: 146740 + 638 = 147378
Step 232: 147378 + 638 = 148016
Step 233: 148016 + 638 = 148654
Step 234: 148654 + 638 = 149292
Step 235: 149292 + 638 = 149930
Step 236: 149930 + 638 = 150568
Step 237: 150568 + 638 = 151206
Step 238: 151206 + 638 = 151844
Step 239: 151844 + 638 = 152482
Step 240: 152482 + 638 = 153120
Step 241: 153120 + 638 = 153758
Step 242: 153758 + 638 = 154396
Step 243: 154396 + 638 = 155034
Step 244: 155034 + 638 = 155672
Step 245: 155672 + 638 = 156310
Step 246: 156310 + 638 = 156948
Step 247: 156948 + 638 = 157586
Step 248: 157586 + 638 = 158224
Step 249: 158224 + 638 = 158862
Step 250: 158862 + 638 = 159500
Step 251: 159500 + 638 = 160138
Step 252: 160138 + 638 = 160776
Step 253: 160776 + 638 = 161414
Step 254: 161414 + 638 = 162052
Step 255: 162052 + 638 = 162690
Step 256: 162690 + 638 = 163328
Step 257: 163328 + 638 = 163966
Step 258: 163966 + 638 = 164604
Step 259: 164604 + 638 = 165242
Step 260: 165242 + 638 = 165880
Step 261: 165880 + 638 = 166518
Step 262: 166518 + 638 = 167156
Step 263: 167156 + 638 = 167794
Step 264: 167794 + 638 = 168432
Step 265: 168432 + 638 = 169070
Step 266: 169070 + 638 = 169708
Step 267: 169708 + 638 = 170346
Step 268: 170346 + 638 = 170984
Step 269: 170984 + 638 = 171622
Step 270: 171622 + 638 = 172260
Step 271: 172260 + 638 = 172898
Step 272: 172898 + 638 = 173536
Step 273: 173536 + 638 = 174174
Step 274: 174174 + 638 = 174812
Step 275: 174812 + 638 = 175450
Step 276: 175450 + 638 = 176088
Step 277: 176088 + 638 = 176726
Step 278: 176726 + 638 = 177364
Step 279: 177364 + 638 = 178002
Step 280: 178002 + 638 = 178640
Step 281: 178640 + 638 = 179278
Step 282: 179278 + 638 = 179916
Step 283: 179916 + 638 = 180554
Step 284: 180554 + 638 = 181192
Step 285: 181192 + 638 = 181830
Step 286: 181830 + 638 = 182468
Step 287: 182468 + 638 = 183106
Step 288: 183106 + 638 = 183744
Step 289: 183744 + 638 = 184382
Step 290: 184382 + 638 = 185020
Step 291: 185020 + 638 = 185658
Step 292: 185658 + 638 = 186296
Step 293: 186296 + 638 = 186934
Step 294: 186934 + 638 = 187572
Step 295: 187572 + 638 = 188210
Step 296: 188210 + 638 = 188848
Step 297: 188848 + 638 = 189486
Step 298: 189486 + 638 = 190124
Step 299: 190124 + 638 = 190762
Step 300: 190762 + 638 = 191400
Step 301: 191400 + 638 = 192038
Step 302: 192038 + 638 = 192676
Step 303: 192676 + 638 = 193314
Step 304: 193314 + 638 = 193952
Step 305: 193952 + 638 = 194590
Step 306: 194590 + 638 = 195228
Step 307: 195228 + 638 = 195866
Step 308: 195866 + 638 = 196504
Step 309: 196504 + 638 = 197142
Step 310: 197142 + 638 = 197780
Step 311: 197780 + 638 = 198418
Step 312: 198418 + 638 = 199056
Step 313: 199056 + 638 = 199694
Step 314: 199694 + 638 = 200332
Step 315: 200332 + 638 = 200970
Step 316: 200970 + 638 = 201608
Step 317: 201608 + 638 = 202246
Step 318: 202246 + 638 = 202884
Step 319: 202884 + 638 = 203522
Step 320: 203522 + 638 = 204160
Step 321: 204160 + 638 = 204798
Step 322: 204798 + 638 = 205436
Step 323: 205436 + 638 = 206074
Step 324: 206074 + 638 = 206712
Step 325: 206712 + 638 = 207350
Step 326: 207350 + 638 = 207988
Step 327: 207988 + 638 = 208626
Step 328: 208626 + 638 = 209264
Step 329: 209264 + 638 = 209902
Step 330: 209902 + 638 = 210540
Step 331: 210540 + 638 = 211178
Step 332: 211178 + 638 = 211816
Step 333: 211816 + 638 = 212454
Step 334: 212454 + 638 = 213092
Step 335: 213092 + 638 = 213730
Step 336: 213730 + 638 = 214368
Step 337: 214368 + 638 = 215006
Step 338: 215006 + 638 = 215644
Step 339: 215644 + 638 = 216282
Step 340: 216282 + 638 = 216920
Step 341: 216920 + 638 = 217558
Step 342: 217558 + 638 = 218196
Step 343: 218196 + 638 = 218834
Step 344: 218834 + 638 = 219472
Step 345: 219472 + 638 = 220110
Step 346: 220110 + 638 = 220748
Step 347: 220748 + 638 = 221386
Step 348: 221386 + 638 = 222024
Step 349: 222024 + 638 = 222662
Step 350: 222662 + 638 = 223300
Step 351: 223300 + 638 = 223938
Step 352: 223938 + 638 = 224576
Step 353: 224576 + 638 = 225214
Step 354: 225214 + 638 = 225852
Step 355: 225852 + 638 = 226490
Step 356: 226490 + 638 = 227128
Step 357: 227128 + 638 = 227766
Step 358: 227766 + 638 = 228404
Step 359: 228404 + 638 = 229042
Step 360: 229042 + 638 = 229680
Step 361: 229680 + 638 = 230318
Step 362: 230318 + 638 = 230956
Step 363: 230956 + 638 = 231594
Step 364: 231594 + 638 = 232232
Step 365: 232232 + 638 = 232870
Step 366: 232870 + 638 = 233508
Step 367: 233508 + 638 = 234146
Step 368: 234146 + 638 = 234784
Step 369: 234784 + 638 = 235422
Step 370: 235422 + 638 = 236060
Step 371: 236060 + 638 = 236698
Step 372: 236698 + 638 = 237336
Step 373: 237336 + 638 = 237974
Step 374: 237974 + 638 = 238612
Step 375: 238612 + 638 = 239250
Step 376: 239250 + 638 = 239888
Step 377: 239888 + 638 = 240526
Step 378: 240526 + 638 = 241164
Step 379: 241164 + 638 = 241802
Step 380: 241802 + 638 = 242440
Step 381: 242440 + 638 = 243078
Step 382: 243078 + 638 = 243716
Step 383: 243716 + 638 = 244354
Step 384: 244354 + 638 = 244992
Step 385: 244992 + 638 = 245630
Step 386: 245630 + 638 = 246268
Step 387: 246268 + 638 = 246906
Step 388: 246906 + 638 = 247544
Step 389: 247544 + 638 = 248182
Step 390: 248182 + 638 = 248820
Step 391: 248820 + 638 = 249458
Step 392: 249458 + 638 = 250096
Step 393: 250096 + 638 = 250734
Step 394: 250734 + 638 = 251372
Step 395: 251372 + 638 = 252010
Step 396: 252010 + 638 = 252648
Step 397: 252648 + 638 = 253286
Step 398: 253286 + 638 = 253924
Step 399: 253924 + 638 = 254562
Step 400: 254562 + 638 = 255200
Step 401: 255200 + 638 = 255838
Step 402: 255838 + 638 = 256476
Step 403: 256476 + 638 = 257114
Step 404: 257114 + 638 = 257752
Step 405: 257752 + 638 = 258390
Step 406: 258390 + 638 = 259028
Step 407: 259028 + 638 = 259666
Step 408: 259666 + 638 = 260304
Step 409: 260304 + 638 = 260942
Step 410: 260942 + 638 = 261580
Step 411: 261580 + 638 = 262218
Step 412: 262218 + 638 = 262856
Step 413: 262856 + 638 = 263494

So, 638*413 = 263494