Without delay, let's solve this. We've got 399 and we will be multiplying it by 89, that is, adding 399 to itself 89 times.
Step 1: 0 + 399 = 399
Step 2: 399 + 399 = 798
Step 3: 798 + 399 = 1197
Step 4: 1197 + 399 = 1596
Step 5: 1596 + 399 = 1995
Step 6: 1995 + 399 = 2394
Step 7: 2394 + 399 = 2793
Step 8: 2793 + 399 = 3192
Step 9: 3192 + 399 = 3591
Step 10: 3591 + 399 = 3990
Step 11: 3990 + 399 = 4389
Step 12: 4389 + 399 = 4788
Step 13: 4788 + 399 = 5187
Step 14: 5187 + 399 = 5586
Step 15: 5586 + 399 = 5985
Step 16: 5985 + 399 = 6384
Step 17: 6384 + 399 = 6783
Step 18: 6783 + 399 = 7182
Step 19: 7182 + 399 = 7581
Step 20: 7581 + 399 = 7980
Step 21: 7980 + 399 = 8379
Step 22: 8379 + 399 = 8778
Step 23: 8778 + 399 = 9177
Step 24: 9177 + 399 = 9576
Step 25: 9576 + 399 = 9975
Step 26: 9975 + 399 = 10374
Step 27: 10374 + 399 = 10773
Step 28: 10773 + 399 = 11172
Step 29: 11172 + 399 = 11571
Step 30: 11571 + 399 = 11970
Step 31: 11970 + 399 = 12369
Step 32: 12369 + 399 = 12768
Step 33: 12768 + 399 = 13167
Step 34: 13167 + 399 = 13566
Step 35: 13566 + 399 = 13965
Step 36: 13965 + 399 = 14364
Step 37: 14364 + 399 = 14763
Step 38: 14763 + 399 = 15162
Step 39: 15162 + 399 = 15561
Step 40: 15561 + 399 = 15960
Step 41: 15960 + 399 = 16359
Step 42: 16359 + 399 = 16758
Step 43: 16758 + 399 = 17157
Step 44: 17157 + 399 = 17556
Step 45: 17556 + 399 = 17955
Step 46: 17955 + 399 = 18354
Step 47: 18354 + 399 = 18753
Step 48: 18753 + 399 = 19152
Step 49: 19152 + 399 = 19551
Step 50: 19551 + 399 = 19950
Step 51: 19950 + 399 = 20349
Step 52: 20349 + 399 = 20748
Step 53: 20748 + 399 = 21147
Step 54: 21147 + 399 = 21546
Step 55: 21546 + 399 = 21945
Step 56: 21945 + 399 = 22344
Step 57: 22344 + 399 = 22743
Step 58: 22743 + 399 = 23142
Step 59: 23142 + 399 = 23541
Step 60: 23541 + 399 = 23940
Step 61: 23940 + 399 = 24339
Step 62: 24339 + 399 = 24738
Step 63: 24738 + 399 = 25137
Step 64: 25137 + 399 = 25536
Step 65: 25536 + 399 = 25935
Step 66: 25935 + 399 = 26334
Step 67: 26334 + 399 = 26733
Step 68: 26733 + 399 = 27132
Step 69: 27132 + 399 = 27531
Step 70: 27531 + 399 = 27930
Step 71: 27930 + 399 = 28329
Step 72: 28329 + 399 = 28728
Step 73: 28728 + 399 = 29127
Step 74: 29127 + 399 = 29526
Step 75: 29526 + 399 = 29925
Step 76: 29925 + 399 = 30324
Step 77: 30324 + 399 = 30723
Step 78: 30723 + 399 = 31122
Step 79: 31122 + 399 = 31521
Step 80: 31521 + 399 = 31920
Step 81: 31920 + 399 = 32319
Step 82: 32319 + 399 = 32718
Step 83: 32718 + 399 = 33117
Step 84: 33117 + 399 = 33516
Step 85: 33516 + 399 = 33915
Step 86: 33915 + 399 = 34314
Step 87: 34314 + 399 = 34713
Step 88: 34713 + 399 = 35112
Step 89: 35112 + 399 = 35511

So, 399*89 = 35511