Alright, let's solve this math problem step by step. First, we have the number 643. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 340. So, we're going to take the number 643 and add it to itself 340 times.
Step 1: 0 + 643 = 643
Step 2: 643 + 643 = 1286
Step 3: 1286 + 643 = 1929
Step 4: 1929 + 643 = 2572
Step 5: 2572 + 643 = 3215
Step 6: 3215 + 643 = 3858
Step 7: 3858 + 643 = 4501
Step 8: 4501 + 643 = 5144
Step 9: 5144 + 643 = 5787
Step 10: 5787 + 643 = 6430
Step 11: 6430 + 643 = 7073
Step 12: 7073 + 643 = 7716
Step 13: 7716 + 643 = 8359
Step 14: 8359 + 643 = 9002
Step 15: 9002 + 643 = 9645
Step 16: 9645 + 643 = 10288
Step 17: 10288 + 643 = 10931
Step 18: 10931 + 643 = 11574
Step 19: 11574 + 643 = 12217
Step 20: 12217 + 643 = 12860
Step 21: 12860 + 643 = 13503
Step 22: 13503 + 643 = 14146
Step 23: 14146 + 643 = 14789
Step 24: 14789 + 643 = 15432
Step 25: 15432 + 643 = 16075
Step 26: 16075 + 643 = 16718
Step 27: 16718 + 643 = 17361
Step 28: 17361 + 643 = 18004
Step 29: 18004 + 643 = 18647
Step 30: 18647 + 643 = 19290
Step 31: 19290 + 643 = 19933
Step 32: 19933 + 643 = 20576
Step 33: 20576 + 643 = 21219
Step 34: 21219 + 643 = 21862
Step 35: 21862 + 643 = 22505
Step 36: 22505 + 643 = 23148
Step 37: 23148 + 643 = 23791
Step 38: 23791 + 643 = 24434
Step 39: 24434 + 643 = 25077
Step 40: 25077 + 643 = 25720
Step 41: 25720 + 643 = 26363
Step 42: 26363 + 643 = 27006
Step 43: 27006 + 643 = 27649
Step 44: 27649 + 643 = 28292
Step 45: 28292 + 643 = 28935
Step 46: 28935 + 643 = 29578
Step 47: 29578 + 643 = 30221
Step 48: 30221 + 643 = 30864
Step 49: 30864 + 643 = 31507
Step 50: 31507 + 643 = 32150
Step 51: 32150 + 643 = 32793
Step 52: 32793 + 643 = 33436
Step 53: 33436 + 643 = 34079
Step 54: 34079 + 643 = 34722
Step 55: 34722 + 643 = 35365
Step 56: 35365 + 643 = 36008
Step 57: 36008 + 643 = 36651
Step 58: 36651 + 643 = 37294
Step 59: 37294 + 643 = 37937
Step 60: 37937 + 643 = 38580
Step 61: 38580 + 643 = 39223
Step 62: 39223 + 643 = 39866
Step 63: 39866 + 643 = 40509
Step 64: 40509 + 643 = 41152
Step 65: 41152 + 643 = 41795
Step 66: 41795 + 643 = 42438
Step 67: 42438 + 643 = 43081
Step 68: 43081 + 643 = 43724
Step 69: 43724 + 643 = 44367
Step 70: 44367 + 643 = 45010
Step 71: 45010 + 643 = 45653
Step 72: 45653 + 643 = 46296
Step 73: 46296 + 643 = 46939
Step 74: 46939 + 643 = 47582
Step 75: 47582 + 643 = 48225
Step 76: 48225 + 643 = 48868
Step 77: 48868 + 643 = 49511
Step 78: 49511 + 643 = 50154
Step 79: 50154 + 643 = 50797
Step 80: 50797 + 643 = 51440
Step 81: 51440 + 643 = 52083
Step 82: 52083 + 643 = 52726
Step 83: 52726 + 643 = 53369
Step 84: 53369 + 643 = 54012
Step 85: 54012 + 643 = 54655
Step 86: 54655 + 643 = 55298
Step 87: 55298 + 643 = 55941
Step 88: 55941 + 643 = 56584
Step 89: 56584 + 643 = 57227
Step 90: 57227 + 643 = 57870
Step 91: 57870 + 643 = 58513
Step 92: 58513 + 643 = 59156
Step 93: 59156 + 643 = 59799
Step 94: 59799 + 643 = 60442
Step 95: 60442 + 643 = 61085
Step 96: 61085 + 643 = 61728
Step 97: 61728 + 643 = 62371
Step 98: 62371 + 643 = 63014
Step 99: 63014 + 643 = 63657
Step 100: 63657 + 643 = 64300
Step 101: 64300 + 643 = 64943
Step 102: 64943 + 643 = 65586
Step 103: 65586 + 643 = 66229
Step 104: 66229 + 643 = 66872
Step 105: 66872 + 643 = 67515
Step 106: 67515 + 643 = 68158
Step 107: 68158 + 643 = 68801
Step 108: 68801 + 643 = 69444
Step 109: 69444 + 643 = 70087
Step 110: 70087 + 643 = 70730
Step 111: 70730 + 643 = 71373
Step 112: 71373 + 643 = 72016
Step 113: 72016 + 643 = 72659
Step 114: 72659 + 643 = 73302
Step 115: 73302 + 643 = 73945
Step 116: 73945 + 643 = 74588
Step 117: 74588 + 643 = 75231
Step 118: 75231 + 643 = 75874
Step 119: 75874 + 643 = 76517
Step 120: 76517 + 643 = 77160
Step 121: 77160 + 643 = 77803
Step 122: 77803 + 643 = 78446
Step 123: 78446 + 643 = 79089
Step 124: 79089 + 643 = 79732
Step 125: 79732 + 643 = 80375
Step 126: 80375 + 643 = 81018
Step 127: 81018 + 643 = 81661
Step 128: 81661 + 643 = 82304
Step 129: 82304 + 643 = 82947
Step 130: 82947 + 643 = 83590
Step 131: 83590 + 643 = 84233
Step 132: 84233 + 643 = 84876
Step 133: 84876 + 643 = 85519
Step 134: 85519 + 643 = 86162
Step 135: 86162 + 643 = 86805
Step 136: 86805 + 643 = 87448
Step 137: 87448 + 643 = 88091
Step 138: 88091 + 643 = 88734
Step 139: 88734 + 643 = 89377
Step 140: 89377 + 643 = 90020
Step 141: 90020 + 643 = 90663
Step 142: 90663 + 643 = 91306
Step 143: 91306 + 643 = 91949
Step 144: 91949 + 643 = 92592
Step 145: 92592 + 643 = 93235
Step 146: 93235 + 643 = 93878
Step 147: 93878 + 643 = 94521
Step 148: 94521 + 643 = 95164
Step 149: 95164 + 643 = 95807
Step 150: 95807 + 643 = 96450
Step 151: 96450 + 643 = 97093
Step 152: 97093 + 643 = 97736
Step 153: 97736 + 643 = 98379
Step 154: 98379 + 643 = 99022
Step 155: 99022 + 643 = 99665
Step 156: 99665 + 643 = 100308
Step 157: 100308 + 643 = 100951
Step 158: 100951 + 643 = 101594
Step 159: 101594 + 643 = 102237
Step 160: 102237 + 643 = 102880
Step 161: 102880 + 643 = 103523
Step 162: 103523 + 643 = 104166
Step 163: 104166 + 643 = 104809
Step 164: 104809 + 643 = 105452
Step 165: 105452 + 643 = 106095
Step 166: 106095 + 643 = 106738
Step 167: 106738 + 643 = 107381
Step 168: 107381 + 643 = 108024
Step 169: 108024 + 643 = 108667
Step 170: 108667 + 643 = 109310
Step 171: 109310 + 643 = 109953
Step 172: 109953 + 643 = 110596
Step 173: 110596 + 643 = 111239
Step 174: 111239 + 643 = 111882
Step 175: 111882 + 643 = 112525
Step 176: 112525 + 643 = 113168
Step 177: 113168 + 643 = 113811
Step 178: 113811 + 643 = 114454
Step 179: 114454 + 643 = 115097
Step 180: 115097 + 643 = 115740
Step 181: 115740 + 643 = 116383
Step 182: 116383 + 643 = 117026
Step 183: 117026 + 643 = 117669
Step 184: 117669 + 643 = 118312
Step 185: 118312 + 643 = 118955
Step 186: 118955 + 643 = 119598
Step 187: 119598 + 643 = 120241
Step 188: 120241 + 643 = 120884
Step 189: 120884 + 643 = 121527
Step 190: 121527 + 643 = 122170
Step 191: 122170 + 643 = 122813
Step 192: 122813 + 643 = 123456
Step 193: 123456 + 643 = 124099
Step 194: 124099 + 643 = 124742
Step 195: 124742 + 643 = 125385
Step 196: 125385 + 643 = 126028
Step 197: 126028 + 643 = 126671
Step 198: 126671 + 643 = 127314
Step 199: 127314 + 643 = 127957
Step 200: 127957 + 643 = 128600
Step 201: 128600 + 643 = 129243
Step 202: 129243 + 643 = 129886
Step 203: 129886 + 643 = 130529
Step 204: 130529 + 643 = 131172
Step 205: 131172 + 643 = 131815
Step 206: 131815 + 643 = 132458
Step 207: 132458 + 643 = 133101
Step 208: 133101 + 643 = 133744
Step 209: 133744 + 643 = 134387
Step 210: 134387 + 643 = 135030
Step 211: 135030 + 643 = 135673
Step 212: 135673 + 643 = 136316
Step 213: 136316 + 643 = 136959
Step 214: 136959 + 643 = 137602
Step 215: 137602 + 643 = 138245
Step 216: 138245 + 643 = 138888
Step 217: 138888 + 643 = 139531
Step 218: 139531 + 643 = 140174
Step 219: 140174 + 643 = 140817
Step 220: 140817 + 643 = 141460
Step 221: 141460 + 643 = 142103
Step 222: 142103 + 643 = 142746
Step 223: 142746 + 643 = 143389
Step 224: 143389 + 643 = 144032
Step 225: 144032 + 643 = 144675
Step 226: 144675 + 643 = 145318
Step 227: 145318 + 643 = 145961
Step 228: 145961 + 643 = 146604
Step 229: 146604 + 643 = 147247
Step 230: 147247 + 643 = 147890
Step 231: 147890 + 643 = 148533
Step 232: 148533 + 643 = 149176
Step 233: 149176 + 643 = 149819
Step 234: 149819 + 643 = 150462
Step 235: 150462 + 643 = 151105
Step 236: 151105 + 643 = 151748
Step 237: 151748 + 643 = 152391
Step 238: 152391 + 643 = 153034
Step 239: 153034 + 643 = 153677
Step 240: 153677 + 643 = 154320
Step 241: 154320 + 643 = 154963
Step 242: 154963 + 643 = 155606
Step 243: 155606 + 643 = 156249
Step 244: 156249 + 643 = 156892
Step 245: 156892 + 643 = 157535
Step 246: 157535 + 643 = 158178
Step 247: 158178 + 643 = 158821
Step 248: 158821 + 643 = 159464
Step 249: 159464 + 643 = 160107
Step 250: 160107 + 643 = 160750
Step 251: 160750 + 643 = 161393
Step 252: 161393 + 643 = 162036
Step 253: 162036 + 643 = 162679
Step 254: 162679 + 643 = 163322
Step 255: 163322 + 643 = 163965
Step 256: 163965 + 643 = 164608
Step 257: 164608 + 643 = 165251
Step 258: 165251 + 643 = 165894
Step 259: 165894 + 643 = 166537
Step 260: 166537 + 643 = 167180
Step 261: 167180 + 643 = 167823
Step 262: 167823 + 643 = 168466
Step 263: 168466 + 643 = 169109
Step 264: 169109 + 643 = 169752
Step 265: 169752 + 643 = 170395
Step 266: 170395 + 643 = 171038
Step 267: 171038 + 643 = 171681
Step 268: 171681 + 643 = 172324
Step 269: 172324 + 643 = 172967
Step 270: 172967 + 643 = 173610
Step 271: 173610 + 643 = 174253
Step 272: 174253 + 643 = 174896
Step 273: 174896 + 643 = 175539
Step 274: 175539 + 643 = 176182
Step 275: 176182 + 643 = 176825
Step 276: 176825 + 643 = 177468
Step 277: 177468 + 643 = 178111
Step 278: 178111 + 643 = 178754
Step 279: 178754 + 643 = 179397
Step 280: 179397 + 643 = 180040
Step 281: 180040 + 643 = 180683
Step 282: 180683 + 643 = 181326
Step 283: 181326 + 643 = 181969
Step 284: 181969 + 643 = 182612
Step 285: 182612 + 643 = 183255
Step 286: 183255 + 643 = 183898
Step 287: 183898 + 643 = 184541
Step 288: 184541 + 643 = 185184
Step 289: 185184 + 643 = 185827
Step 290: 185827 + 643 = 186470
Step 291: 186470 + 643 = 187113
Step 292: 187113 + 643 = 187756
Step 293: 187756 + 643 = 188399
Step 294: 188399 + 643 = 189042
Step 295: 189042 + 643 = 189685
Step 296: 189685 + 643 = 190328
Step 297: 190328 + 643 = 190971
Step 298: 190971 + 643 = 191614
Step 299: 191614 + 643 = 192257
Step 300: 192257 + 643 = 192900
Step 301: 192900 + 643 = 193543
Step 302: 193543 + 643 = 194186
Step 303: 194186 + 643 = 194829
Step 304: 194829 + 643 = 195472
Step 305: 195472 + 643 = 196115
Step 306: 196115 + 643 = 196758
Step 307: 196758 + 643 = 197401
Step 308: 197401 + 643 = 198044
Step 309: 198044 + 643 = 198687
Step 310: 198687 + 643 = 199330
Step 311: 199330 + 643 = 199973
Step 312: 199973 + 643 = 200616
Step 313: 200616 + 643 = 201259
Step 314: 201259 + 643 = 201902
Step 315: 201902 + 643 = 202545
Step 316: 202545 + 643 = 203188
Step 317: 203188 + 643 = 203831
Step 318: 203831 + 643 = 204474
Step 319: 204474 + 643 = 205117
Step 320: 205117 + 643 = 205760
Step 321: 205760 + 643 = 206403
Step 322: 206403 + 643 = 207046
Step 323: 207046 + 643 = 207689
Step 324: 207689 + 643 = 208332
Step 325: 208332 + 643 = 208975
Step 326: 208975 + 643 = 209618
Step 327: 209618 + 643 = 210261
Step 328: 210261 + 643 = 210904
Step 329: 210904 + 643 = 211547
Step 330: 211547 + 643 = 212190
Step 331: 212190 + 643 = 212833
Step 332: 212833 + 643 = 213476
Step 333: 213476 + 643 = 214119
Step 334: 214119 + 643 = 214762
Step 335: 214762 + 643 = 215405
Step 336: 215405 + 643 = 216048
Step 337: 216048 + 643 = 216691
Step 338: 216691 + 643 = 217334
Step 339: 217334 + 643 = 217977
Step 340: 217977 + 643 = 218620

So, 643*340 = 218620