Alright, let's solve this math problem step by step. First, we have the number 831. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 420. So, we're going to take the number 831 and add it to itself 420 times.
Step 1: 0 + 831 = 831
Step 2: 831 + 831 = 1662
Step 3: 1662 + 831 = 2493
Step 4: 2493 + 831 = 3324
Step 5: 3324 + 831 = 4155
Step 6: 4155 + 831 = 4986
Step 7: 4986 + 831 = 5817
Step 8: 5817 + 831 = 6648
Step 9: 6648 + 831 = 7479
Step 10: 7479 + 831 = 8310
Step 11: 8310 + 831 = 9141
Step 12: 9141 + 831 = 9972
Step 13: 9972 + 831 = 10803
Step 14: 10803 + 831 = 11634
Step 15: 11634 + 831 = 12465
Step 16: 12465 + 831 = 13296
Step 17: 13296 + 831 = 14127
Step 18: 14127 + 831 = 14958
Step 19: 14958 + 831 = 15789
Step 20: 15789 + 831 = 16620
Step 21: 16620 + 831 = 17451
Step 22: 17451 + 831 = 18282
Step 23: 18282 + 831 = 19113
Step 24: 19113 + 831 = 19944
Step 25: 19944 + 831 = 20775
Step 26: 20775 + 831 = 21606
Step 27: 21606 + 831 = 22437
Step 28: 22437 + 831 = 23268
Step 29: 23268 + 831 = 24099
Step 30: 24099 + 831 = 24930
Step 31: 24930 + 831 = 25761
Step 32: 25761 + 831 = 26592
Step 33: 26592 + 831 = 27423
Step 34: 27423 + 831 = 28254
Step 35: 28254 + 831 = 29085
Step 36: 29085 + 831 = 29916
Step 37: 29916 + 831 = 30747
Step 38: 30747 + 831 = 31578
Step 39: 31578 + 831 = 32409
Step 40: 32409 + 831 = 33240
Step 41: 33240 + 831 = 34071
Step 42: 34071 + 831 = 34902
Step 43: 34902 + 831 = 35733
Step 44: 35733 + 831 = 36564
Step 45: 36564 + 831 = 37395
Step 46: 37395 + 831 = 38226
Step 47: 38226 + 831 = 39057
Step 48: 39057 + 831 = 39888
Step 49: 39888 + 831 = 40719
Step 50: 40719 + 831 = 41550
Step 51: 41550 + 831 = 42381
Step 52: 42381 + 831 = 43212
Step 53: 43212 + 831 = 44043
Step 54: 44043 + 831 = 44874
Step 55: 44874 + 831 = 45705
Step 56: 45705 + 831 = 46536
Step 57: 46536 + 831 = 47367
Step 58: 47367 + 831 = 48198
Step 59: 48198 + 831 = 49029
Step 60: 49029 + 831 = 49860
Step 61: 49860 + 831 = 50691
Step 62: 50691 + 831 = 51522
Step 63: 51522 + 831 = 52353
Step 64: 52353 + 831 = 53184
Step 65: 53184 + 831 = 54015
Step 66: 54015 + 831 = 54846
Step 67: 54846 + 831 = 55677
Step 68: 55677 + 831 = 56508
Step 69: 56508 + 831 = 57339
Step 70: 57339 + 831 = 58170
Step 71: 58170 + 831 = 59001
Step 72: 59001 + 831 = 59832
Step 73: 59832 + 831 = 60663
Step 74: 60663 + 831 = 61494
Step 75: 61494 + 831 = 62325
Step 76: 62325 + 831 = 63156
Step 77: 63156 + 831 = 63987
Step 78: 63987 + 831 = 64818
Step 79: 64818 + 831 = 65649
Step 80: 65649 + 831 = 66480
Step 81: 66480 + 831 = 67311
Step 82: 67311 + 831 = 68142
Step 83: 68142 + 831 = 68973
Step 84: 68973 + 831 = 69804
Step 85: 69804 + 831 = 70635
Step 86: 70635 + 831 = 71466
Step 87: 71466 + 831 = 72297
Step 88: 72297 + 831 = 73128
Step 89: 73128 + 831 = 73959
Step 90: 73959 + 831 = 74790
Step 91: 74790 + 831 = 75621
Step 92: 75621 + 831 = 76452
Step 93: 76452 + 831 = 77283
Step 94: 77283 + 831 = 78114
Step 95: 78114 + 831 = 78945
Step 96: 78945 + 831 = 79776
Step 97: 79776 + 831 = 80607
Step 98: 80607 + 831 = 81438
Step 99: 81438 + 831 = 82269
Step 100: 82269 + 831 = 83100
Step 101: 83100 + 831 = 83931
Step 102: 83931 + 831 = 84762
Step 103: 84762 + 831 = 85593
Step 104: 85593 + 831 = 86424
Step 105: 86424 + 831 = 87255
Step 106: 87255 + 831 = 88086
Step 107: 88086 + 831 = 88917
Step 108: 88917 + 831 = 89748
Step 109: 89748 + 831 = 90579
Step 110: 90579 + 831 = 91410
Step 111: 91410 + 831 = 92241
Step 112: 92241 + 831 = 93072
Step 113: 93072 + 831 = 93903
Step 114: 93903 + 831 = 94734
Step 115: 94734 + 831 = 95565
Step 116: 95565 + 831 = 96396
Step 117: 96396 + 831 = 97227
Step 118: 97227 + 831 = 98058
Step 119: 98058 + 831 = 98889
Step 120: 98889 + 831 = 99720
Step 121: 99720 + 831 = 100551
Step 122: 100551 + 831 = 101382
Step 123: 101382 + 831 = 102213
Step 124: 102213 + 831 = 103044
Step 125: 103044 + 831 = 103875
Step 126: 103875 + 831 = 104706
Step 127: 104706 + 831 = 105537
Step 128: 105537 + 831 = 106368
Step 129: 106368 + 831 = 107199
Step 130: 107199 + 831 = 108030
Step 131: 108030 + 831 = 108861
Step 132: 108861 + 831 = 109692
Step 133: 109692 + 831 = 110523
Step 134: 110523 + 831 = 111354
Step 135: 111354 + 831 = 112185
Step 136: 112185 + 831 = 113016
Step 137: 113016 + 831 = 113847
Step 138: 113847 + 831 = 114678
Step 139: 114678 + 831 = 115509
Step 140: 115509 + 831 = 116340
Step 141: 116340 + 831 = 117171
Step 142: 117171 + 831 = 118002
Step 143: 118002 + 831 = 118833
Step 144: 118833 + 831 = 119664
Step 145: 119664 + 831 = 120495
Step 146: 120495 + 831 = 121326
Step 147: 121326 + 831 = 122157
Step 148: 122157 + 831 = 122988
Step 149: 122988 + 831 = 123819
Step 150: 123819 + 831 = 124650
Step 151: 124650 + 831 = 125481
Step 152: 125481 + 831 = 126312
Step 153: 126312 + 831 = 127143
Step 154: 127143 + 831 = 127974
Step 155: 127974 + 831 = 128805
Step 156: 128805 + 831 = 129636
Step 157: 129636 + 831 = 130467
Step 158: 130467 + 831 = 131298
Step 159: 131298 + 831 = 132129
Step 160: 132129 + 831 = 132960
Step 161: 132960 + 831 = 133791
Step 162: 133791 + 831 = 134622
Step 163: 134622 + 831 = 135453
Step 164: 135453 + 831 = 136284
Step 165: 136284 + 831 = 137115
Step 166: 137115 + 831 = 137946
Step 167: 137946 + 831 = 138777
Step 168: 138777 + 831 = 139608
Step 169: 139608 + 831 = 140439
Step 170: 140439 + 831 = 141270
Step 171: 141270 + 831 = 142101
Step 172: 142101 + 831 = 142932
Step 173: 142932 + 831 = 143763
Step 174: 143763 + 831 = 144594
Step 175: 144594 + 831 = 145425
Step 176: 145425 + 831 = 146256
Step 177: 146256 + 831 = 147087
Step 178: 147087 + 831 = 147918
Step 179: 147918 + 831 = 148749
Step 180: 148749 + 831 = 149580
Step 181: 149580 + 831 = 150411
Step 182: 150411 + 831 = 151242
Step 183: 151242 + 831 = 152073
Step 184: 152073 + 831 = 152904
Step 185: 152904 + 831 = 153735
Step 186: 153735 + 831 = 154566
Step 187: 154566 + 831 = 155397
Step 188: 155397 + 831 = 156228
Step 189: 156228 + 831 = 157059
Step 190: 157059 + 831 = 157890
Step 191: 157890 + 831 = 158721
Step 192: 158721 + 831 = 159552
Step 193: 159552 + 831 = 160383
Step 194: 160383 + 831 = 161214
Step 195: 161214 + 831 = 162045
Step 196: 162045 + 831 = 162876
Step 197: 162876 + 831 = 163707
Step 198: 163707 + 831 = 164538
Step 199: 164538 + 831 = 165369
Step 200: 165369 + 831 = 166200
Step 201: 166200 + 831 = 167031
Step 202: 167031 + 831 = 167862
Step 203: 167862 + 831 = 168693
Step 204: 168693 + 831 = 169524
Step 205: 169524 + 831 = 170355
Step 206: 170355 + 831 = 171186
Step 207: 171186 + 831 = 172017
Step 208: 172017 + 831 = 172848
Step 209: 172848 + 831 = 173679
Step 210: 173679 + 831 = 174510
Step 211: 174510 + 831 = 175341
Step 212: 175341 + 831 = 176172
Step 213: 176172 + 831 = 177003
Step 214: 177003 + 831 = 177834
Step 215: 177834 + 831 = 178665
Step 216: 178665 + 831 = 179496
Step 217: 179496 + 831 = 180327
Step 218: 180327 + 831 = 181158
Step 219: 181158 + 831 = 181989
Step 220: 181989 + 831 = 182820
Step 221: 182820 + 831 = 183651
Step 222: 183651 + 831 = 184482
Step 223: 184482 + 831 = 185313
Step 224: 185313 + 831 = 186144
Step 225: 186144 + 831 = 186975
Step 226: 186975 + 831 = 187806
Step 227: 187806 + 831 = 188637
Step 228: 188637 + 831 = 189468
Step 229: 189468 + 831 = 190299
Step 230: 190299 + 831 = 191130
Step 231: 191130 + 831 = 191961
Step 232: 191961 + 831 = 192792
Step 233: 192792 + 831 = 193623
Step 234: 193623 + 831 = 194454
Step 235: 194454 + 831 = 195285
Step 236: 195285 + 831 = 196116
Step 237: 196116 + 831 = 196947
Step 238: 196947 + 831 = 197778
Step 239: 197778 + 831 = 198609
Step 240: 198609 + 831 = 199440
Step 241: 199440 + 831 = 200271
Step 242: 200271 + 831 = 201102
Step 243: 201102 + 831 = 201933
Step 244: 201933 + 831 = 202764
Step 245: 202764 + 831 = 203595
Step 246: 203595 + 831 = 204426
Step 247: 204426 + 831 = 205257
Step 248: 205257 + 831 = 206088
Step 249: 206088 + 831 = 206919
Step 250: 206919 + 831 = 207750
Step 251: 207750 + 831 = 208581
Step 252: 208581 + 831 = 209412
Step 253: 209412 + 831 = 210243
Step 254: 210243 + 831 = 211074
Step 255: 211074 + 831 = 211905
Step 256: 211905 + 831 = 212736
Step 257: 212736 + 831 = 213567
Step 258: 213567 + 831 = 214398
Step 259: 214398 + 831 = 215229
Step 260: 215229 + 831 = 216060
Step 261: 216060 + 831 = 216891
Step 262: 216891 + 831 = 217722
Step 263: 217722 + 831 = 218553
Step 264: 218553 + 831 = 219384
Step 265: 219384 + 831 = 220215
Step 266: 220215 + 831 = 221046
Step 267: 221046 + 831 = 221877
Step 268: 221877 + 831 = 222708
Step 269: 222708 + 831 = 223539
Step 270: 223539 + 831 = 224370
Step 271: 224370 + 831 = 225201
Step 272: 225201 + 831 = 226032
Step 273: 226032 + 831 = 226863
Step 274: 226863 + 831 = 227694
Step 275: 227694 + 831 = 228525
Step 276: 228525 + 831 = 229356
Step 277: 229356 + 831 = 230187
Step 278: 230187 + 831 = 231018
Step 279: 231018 + 831 = 231849
Step 280: 231849 + 831 = 232680
Step 281: 232680 + 831 = 233511
Step 282: 233511 + 831 = 234342
Step 283: 234342 + 831 = 235173
Step 284: 235173 + 831 = 236004
Step 285: 236004 + 831 = 236835
Step 286: 236835 + 831 = 237666
Step 287: 237666 + 831 = 238497
Step 288: 238497 + 831 = 239328
Step 289: 239328 + 831 = 240159
Step 290: 240159 + 831 = 240990
Step 291: 240990 + 831 = 241821
Step 292: 241821 + 831 = 242652
Step 293: 242652 + 831 = 243483
Step 294: 243483 + 831 = 244314
Step 295: 244314 + 831 = 245145
Step 296: 245145 + 831 = 245976
Step 297: 245976 + 831 = 246807
Step 298: 246807 + 831 = 247638
Step 299: 247638 + 831 = 248469
Step 300: 248469 + 831 = 249300
Step 301: 249300 + 831 = 250131
Step 302: 250131 + 831 = 250962
Step 303: 250962 + 831 = 251793
Step 304: 251793 + 831 = 252624
Step 305: 252624 + 831 = 253455
Step 306: 253455 + 831 = 254286
Step 307: 254286 + 831 = 255117
Step 308: 255117 + 831 = 255948
Step 309: 255948 + 831 = 256779
Step 310: 256779 + 831 = 257610
Step 311: 257610 + 831 = 258441
Step 312: 258441 + 831 = 259272
Step 313: 259272 + 831 = 260103
Step 314: 260103 + 831 = 260934
Step 315: 260934 + 831 = 261765
Step 316: 261765 + 831 = 262596
Step 317: 262596 + 831 = 263427
Step 318: 263427 + 831 = 264258
Step 319: 264258 + 831 = 265089
Step 320: 265089 + 831 = 265920
Step 321: 265920 + 831 = 266751
Step 322: 266751 + 831 = 267582
Step 323: 267582 + 831 = 268413
Step 324: 268413 + 831 = 269244
Step 325: 269244 + 831 = 270075
Step 326: 270075 + 831 = 270906
Step 327: 270906 + 831 = 271737
Step 328: 271737 + 831 = 272568
Step 329: 272568 + 831 = 273399
Step 330: 273399 + 831 = 274230
Step 331: 274230 + 831 = 275061
Step 332: 275061 + 831 = 275892
Step 333: 275892 + 831 = 276723
Step 334: 276723 + 831 = 277554
Step 335: 277554 + 831 = 278385
Step 336: 278385 + 831 = 279216
Step 337: 279216 + 831 = 280047
Step 338: 280047 + 831 = 280878
Step 339: 280878 + 831 = 281709
Step 340: 281709 + 831 = 282540
Step 341: 282540 + 831 = 283371
Step 342: 283371 + 831 = 284202
Step 343: 284202 + 831 = 285033
Step 344: 285033 + 831 = 285864
Step 345: 285864 + 831 = 286695
Step 346: 286695 + 831 = 287526
Step 347: 287526 + 831 = 288357
Step 348: 288357 + 831 = 289188
Step 349: 289188 + 831 = 290019
Step 350: 290019 + 831 = 290850
Step 351: 290850 + 831 = 291681
Step 352: 291681 + 831 = 292512
Step 353: 292512 + 831 = 293343
Step 354: 293343 + 831 = 294174
Step 355: 294174 + 831 = 295005
Step 356: 295005 + 831 = 295836
Step 357: 295836 + 831 = 296667
Step 358: 296667 + 831 = 297498
Step 359: 297498 + 831 = 298329
Step 360: 298329 + 831 = 299160
Step 361: 299160 + 831 = 299991
Step 362: 299991 + 831 = 300822
Step 363: 300822 + 831 = 301653
Step 364: 301653 + 831 = 302484
Step 365: 302484 + 831 = 303315
Step 366: 303315 + 831 = 304146
Step 367: 304146 + 831 = 304977
Step 368: 304977 + 831 = 305808
Step 369: 305808 + 831 = 306639
Step 370: 306639 + 831 = 307470
Step 371: 307470 + 831 = 308301
Step 372: 308301 + 831 = 309132
Step 373: 309132 + 831 = 309963
Step 374: 309963 + 831 = 310794
Step 375: 310794 + 831 = 311625
Step 376: 311625 + 831 = 312456
Step 377: 312456 + 831 = 313287
Step 378: 313287 + 831 = 314118
Step 379: 314118 + 831 = 314949
Step 380: 314949 + 831 = 315780
Step 381: 315780 + 831 = 316611
Step 382: 316611 + 831 = 317442
Step 383: 317442 + 831 = 318273
Step 384: 318273 + 831 = 319104
Step 385: 319104 + 831 = 319935
Step 386: 319935 + 831 = 320766
Step 387: 320766 + 831 = 321597
Step 388: 321597 + 831 = 322428
Step 389: 322428 + 831 = 323259
Step 390: 323259 + 831 = 324090
Step 391: 324090 + 831 = 324921
Step 392: 324921 + 831 = 325752
Step 393: 325752 + 831 = 326583
Step 394: 326583 + 831 = 327414
Step 395: 327414 + 831 = 328245
Step 396: 328245 + 831 = 329076
Step 397: 329076 + 831 = 329907
Step 398: 329907 + 831 = 330738
Step 399: 330738 + 831 = 331569
Step 400: 331569 + 831 = 332400
Step 401: 332400 + 831 = 333231
Step 402: 333231 + 831 = 334062
Step 403: 334062 + 831 = 334893
Step 404: 334893 + 831 = 335724
Step 405: 335724 + 831 = 336555
Step 406: 336555 + 831 = 337386
Step 407: 337386 + 831 = 338217
Step 408: 338217 + 831 = 339048
Step 409: 339048 + 831 = 339879
Step 410: 339879 + 831 = 340710
Step 411: 340710 + 831 = 341541
Step 412: 341541 + 831 = 342372
Step 413: 342372 + 831 = 343203
Step 414: 343203 + 831 = 344034
Step 415: 344034 + 831 = 344865
Step 416: 344865 + 831 = 345696
Step 417: 345696 + 831 = 346527
Step 418: 346527 + 831 = 347358
Step 419: 347358 + 831 = 348189
Step 420: 348189 + 831 = 349020

So, 831*420 = 349020