OK, let's work through this together. We're starting with 623 and we're going to multiply it by 63, which means we add 623 to itself 63 times.
Step 1: 0 + 623 = 623
Step 2: 623 + 623 = 1246
Step 3: 1246 + 623 = 1869
Step 4: 1869 + 623 = 2492
Step 5: 2492 + 623 = 3115
Step 6: 3115 + 623 = 3738
Step 7: 3738 + 623 = 4361
Step 8: 4361 + 623 = 4984
Step 9: 4984 + 623 = 5607
Step 10: 5607 + 623 = 6230
Step 11: 6230 + 623 = 6853
Step 12: 6853 + 623 = 7476
Step 13: 7476 + 623 = 8099
Step 14: 8099 + 623 = 8722
Step 15: 8722 + 623 = 9345
Step 16: 9345 + 623 = 9968
Step 17: 9968 + 623 = 10591
Step 18: 10591 + 623 = 11214
Step 19: 11214 + 623 = 11837
Step 20: 11837 + 623 = 12460
Step 21: 12460 + 623 = 13083
Step 22: 13083 + 623 = 13706
Step 23: 13706 + 623 = 14329
Step 24: 14329 + 623 = 14952
Step 25: 14952 + 623 = 15575
Step 26: 15575 + 623 = 16198
Step 27: 16198 + 623 = 16821
Step 28: 16821 + 623 = 17444
Step 29: 17444 + 623 = 18067
Step 30: 18067 + 623 = 18690
Step 31: 18690 + 623 = 19313
Step 32: 19313 + 623 = 19936
Step 33: 19936 + 623 = 20559
Step 34: 20559 + 623 = 21182
Step 35: 21182 + 623 = 21805
Step 36: 21805 + 623 = 22428
Step 37: 22428 + 623 = 23051
Step 38: 23051 + 623 = 23674
Step 39: 23674 + 623 = 24297
Step 40: 24297 + 623 = 24920
Step 41: 24920 + 623 = 25543
Step 42: 25543 + 623 = 26166
Step 43: 26166 + 623 = 26789
Step 44: 26789 + 623 = 27412
Step 45: 27412 + 623 = 28035
Step 46: 28035 + 623 = 28658
Step 47: 28658 + 623 = 29281
Step 48: 29281 + 623 = 29904
Step 49: 29904 + 623 = 30527
Step 50: 30527 + 623 = 31150
Step 51: 31150 + 623 = 31773
Step 52: 31773 + 623 = 32396
Step 53: 32396 + 623 = 33019
Step 54: 33019 + 623 = 33642
Step 55: 33642 + 623 = 34265
Step 56: 34265 + 623 = 34888
Step 57: 34888 + 623 = 35511
Step 58: 35511 + 623 = 36134
Step 59: 36134 + 623 = 36757
Step 60: 36757 + 623 = 37380
Step 61: 37380 + 623 = 38003
Step 62: 38003 + 623 = 38626
Step 63: 38626 + 623 = 39249

So, 623*63 = 39249