Alright, let's solve this math problem step by step. First, we have the number 644. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 263. So, we're going to take the number 644 and add it to itself 263 times.
Step 1: 0 + 644 = 644
Step 2: 644 + 644 = 1288
Step 3: 1288 + 644 = 1932
Step 4: 1932 + 644 = 2576
Step 5: 2576 + 644 = 3220
Step 6: 3220 + 644 = 3864
Step 7: 3864 + 644 = 4508
Step 8: 4508 + 644 = 5152
Step 9: 5152 + 644 = 5796
Step 10: 5796 + 644 = 6440
Step 11: 6440 + 644 = 7084
Step 12: 7084 + 644 = 7728
Step 13: 7728 + 644 = 8372
Step 14: 8372 + 644 = 9016
Step 15: 9016 + 644 = 9660
Step 16: 9660 + 644 = 10304
Step 17: 10304 + 644 = 10948
Step 18: 10948 + 644 = 11592
Step 19: 11592 + 644 = 12236
Step 20: 12236 + 644 = 12880
Step 21: 12880 + 644 = 13524
Step 22: 13524 + 644 = 14168
Step 23: 14168 + 644 = 14812
Step 24: 14812 + 644 = 15456
Step 25: 15456 + 644 = 16100
Step 26: 16100 + 644 = 16744
Step 27: 16744 + 644 = 17388
Step 28: 17388 + 644 = 18032
Step 29: 18032 + 644 = 18676
Step 30: 18676 + 644 = 19320
Step 31: 19320 + 644 = 19964
Step 32: 19964 + 644 = 20608
Step 33: 20608 + 644 = 21252
Step 34: 21252 + 644 = 21896
Step 35: 21896 + 644 = 22540
Step 36: 22540 + 644 = 23184
Step 37: 23184 + 644 = 23828
Step 38: 23828 + 644 = 24472
Step 39: 24472 + 644 = 25116
Step 40: 25116 + 644 = 25760
Step 41: 25760 + 644 = 26404
Step 42: 26404 + 644 = 27048
Step 43: 27048 + 644 = 27692
Step 44: 27692 + 644 = 28336
Step 45: 28336 + 644 = 28980
Step 46: 28980 + 644 = 29624
Step 47: 29624 + 644 = 30268
Step 48: 30268 + 644 = 30912
Step 49: 30912 + 644 = 31556
Step 50: 31556 + 644 = 32200
Step 51: 32200 + 644 = 32844
Step 52: 32844 + 644 = 33488
Step 53: 33488 + 644 = 34132
Step 54: 34132 + 644 = 34776
Step 55: 34776 + 644 = 35420
Step 56: 35420 + 644 = 36064
Step 57: 36064 + 644 = 36708
Step 58: 36708 + 644 = 37352
Step 59: 37352 + 644 = 37996
Step 60: 37996 + 644 = 38640
Step 61: 38640 + 644 = 39284
Step 62: 39284 + 644 = 39928
Step 63: 39928 + 644 = 40572
Step 64: 40572 + 644 = 41216
Step 65: 41216 + 644 = 41860
Step 66: 41860 + 644 = 42504
Step 67: 42504 + 644 = 43148
Step 68: 43148 + 644 = 43792
Step 69: 43792 + 644 = 44436
Step 70: 44436 + 644 = 45080
Step 71: 45080 + 644 = 45724
Step 72: 45724 + 644 = 46368
Step 73: 46368 + 644 = 47012
Step 74: 47012 + 644 = 47656
Step 75: 47656 + 644 = 48300
Step 76: 48300 + 644 = 48944
Step 77: 48944 + 644 = 49588
Step 78: 49588 + 644 = 50232
Step 79: 50232 + 644 = 50876
Step 80: 50876 + 644 = 51520
Step 81: 51520 + 644 = 52164
Step 82: 52164 + 644 = 52808
Step 83: 52808 + 644 = 53452
Step 84: 53452 + 644 = 54096
Step 85: 54096 + 644 = 54740
Step 86: 54740 + 644 = 55384
Step 87: 55384 + 644 = 56028
Step 88: 56028 + 644 = 56672
Step 89: 56672 + 644 = 57316
Step 90: 57316 + 644 = 57960
Step 91: 57960 + 644 = 58604
Step 92: 58604 + 644 = 59248
Step 93: 59248 + 644 = 59892
Step 94: 59892 + 644 = 60536
Step 95: 60536 + 644 = 61180
Step 96: 61180 + 644 = 61824
Step 97: 61824 + 644 = 62468
Step 98: 62468 + 644 = 63112
Step 99: 63112 + 644 = 63756
Step 100: 63756 + 644 = 64400
Step 101: 64400 + 644 = 65044
Step 102: 65044 + 644 = 65688
Step 103: 65688 + 644 = 66332
Step 104: 66332 + 644 = 66976
Step 105: 66976 + 644 = 67620
Step 106: 67620 + 644 = 68264
Step 107: 68264 + 644 = 68908
Step 108: 68908 + 644 = 69552
Step 109: 69552 + 644 = 70196
Step 110: 70196 + 644 = 70840
Step 111: 70840 + 644 = 71484
Step 112: 71484 + 644 = 72128
Step 113: 72128 + 644 = 72772
Step 114: 72772 + 644 = 73416
Step 115: 73416 + 644 = 74060
Step 116: 74060 + 644 = 74704
Step 117: 74704 + 644 = 75348
Step 118: 75348 + 644 = 75992
Step 119: 75992 + 644 = 76636
Step 120: 76636 + 644 = 77280
Step 121: 77280 + 644 = 77924
Step 122: 77924 + 644 = 78568
Step 123: 78568 + 644 = 79212
Step 124: 79212 + 644 = 79856
Step 125: 79856 + 644 = 80500
Step 126: 80500 + 644 = 81144
Step 127: 81144 + 644 = 81788
Step 128: 81788 + 644 = 82432
Step 129: 82432 + 644 = 83076
Step 130: 83076 + 644 = 83720
Step 131: 83720 + 644 = 84364
Step 132: 84364 + 644 = 85008
Step 133: 85008 + 644 = 85652
Step 134: 85652 + 644 = 86296
Step 135: 86296 + 644 = 86940
Step 136: 86940 + 644 = 87584
Step 137: 87584 + 644 = 88228
Step 138: 88228 + 644 = 88872
Step 139: 88872 + 644 = 89516
Step 140: 89516 + 644 = 90160
Step 141: 90160 + 644 = 90804
Step 142: 90804 + 644 = 91448
Step 143: 91448 + 644 = 92092
Step 144: 92092 + 644 = 92736
Step 145: 92736 + 644 = 93380
Step 146: 93380 + 644 = 94024
Step 147: 94024 + 644 = 94668
Step 148: 94668 + 644 = 95312
Step 149: 95312 + 644 = 95956
Step 150: 95956 + 644 = 96600
Step 151: 96600 + 644 = 97244
Step 152: 97244 + 644 = 97888
Step 153: 97888 + 644 = 98532
Step 154: 98532 + 644 = 99176
Step 155: 99176 + 644 = 99820
Step 156: 99820 + 644 = 100464
Step 157: 100464 + 644 = 101108
Step 158: 101108 + 644 = 101752
Step 159: 101752 + 644 = 102396
Step 160: 102396 + 644 = 103040
Step 161: 103040 + 644 = 103684
Step 162: 103684 + 644 = 104328
Step 163: 104328 + 644 = 104972
Step 164: 104972 + 644 = 105616
Step 165: 105616 + 644 = 106260
Step 166: 106260 + 644 = 106904
Step 167: 106904 + 644 = 107548
Step 168: 107548 + 644 = 108192
Step 169: 108192 + 644 = 108836
Step 170: 108836 + 644 = 109480
Step 171: 109480 + 644 = 110124
Step 172: 110124 + 644 = 110768
Step 173: 110768 + 644 = 111412
Step 174: 111412 + 644 = 112056
Step 175: 112056 + 644 = 112700
Step 176: 112700 + 644 = 113344
Step 177: 113344 + 644 = 113988
Step 178: 113988 + 644 = 114632
Step 179: 114632 + 644 = 115276
Step 180: 115276 + 644 = 115920
Step 181: 115920 + 644 = 116564
Step 182: 116564 + 644 = 117208
Step 183: 117208 + 644 = 117852
Step 184: 117852 + 644 = 118496
Step 185: 118496 + 644 = 119140
Step 186: 119140 + 644 = 119784
Step 187: 119784 + 644 = 120428
Step 188: 120428 + 644 = 121072
Step 189: 121072 + 644 = 121716
Step 190: 121716 + 644 = 122360
Step 191: 122360 + 644 = 123004
Step 192: 123004 + 644 = 123648
Step 193: 123648 + 644 = 124292
Step 194: 124292 + 644 = 124936
Step 195: 124936 + 644 = 125580
Step 196: 125580 + 644 = 126224
Step 197: 126224 + 644 = 126868
Step 198: 126868 + 644 = 127512
Step 199: 127512 + 644 = 128156
Step 200: 128156 + 644 = 128800
Step 201: 128800 + 644 = 129444
Step 202: 129444 + 644 = 130088
Step 203: 130088 + 644 = 130732
Step 204: 130732 + 644 = 131376
Step 205: 131376 + 644 = 132020
Step 206: 132020 + 644 = 132664
Step 207: 132664 + 644 = 133308
Step 208: 133308 + 644 = 133952
Step 209: 133952 + 644 = 134596
Step 210: 134596 + 644 = 135240
Step 211: 135240 + 644 = 135884
Step 212: 135884 + 644 = 136528
Step 213: 136528 + 644 = 137172
Step 214: 137172 + 644 = 137816
Step 215: 137816 + 644 = 138460
Step 216: 138460 + 644 = 139104
Step 217: 139104 + 644 = 139748
Step 218: 139748 + 644 = 140392
Step 219: 140392 + 644 = 141036
Step 220: 141036 + 644 = 141680
Step 221: 141680 + 644 = 142324
Step 222: 142324 + 644 = 142968
Step 223: 142968 + 644 = 143612
Step 224: 143612 + 644 = 144256
Step 225: 144256 + 644 = 144900
Step 226: 144900 + 644 = 145544
Step 227: 145544 + 644 = 146188
Step 228: 146188 + 644 = 146832
Step 229: 146832 + 644 = 147476
Step 230: 147476 + 644 = 148120
Step 231: 148120 + 644 = 148764
Step 232: 148764 + 644 = 149408
Step 233: 149408 + 644 = 150052
Step 234: 150052 + 644 = 150696
Step 235: 150696 + 644 = 151340
Step 236: 151340 + 644 = 151984
Step 237: 151984 + 644 = 152628
Step 238: 152628 + 644 = 153272
Step 239: 153272 + 644 = 153916
Step 240: 153916 + 644 = 154560
Step 241: 154560 + 644 = 155204
Step 242: 155204 + 644 = 155848
Step 243: 155848 + 644 = 156492
Step 244: 156492 + 644 = 157136
Step 245: 157136 + 644 = 157780
Step 246: 157780 + 644 = 158424
Step 247: 158424 + 644 = 159068
Step 248: 159068 + 644 = 159712
Step 249: 159712 + 644 = 160356
Step 250: 160356 + 644 = 161000
Step 251: 161000 + 644 = 161644
Step 252: 161644 + 644 = 162288
Step 253: 162288 + 644 = 162932
Step 254: 162932 + 644 = 163576
Step 255: 163576 + 644 = 164220
Step 256: 164220 + 644 = 164864
Step 257: 164864 + 644 = 165508
Step 258: 165508 + 644 = 166152
Step 259: 166152 + 644 = 166796
Step 260: 166796 + 644 = 167440
Step 261: 167440 + 644 = 168084
Step 262: 168084 + 644 = 168728
Step 263: 168728 + 644 = 169372

So, 644*263 = 169372