Sure thing! We've got 353 and we're gonna multiply it by 81. That's the same as adding 353 to itself 81 times.
Step 1: 0 + 353 = 353
Step 2: 353 + 353 = 706
Step 3: 706 + 353 = 1059
Step 4: 1059 + 353 = 1412
Step 5: 1412 + 353 = 1765
Step 6: 1765 + 353 = 2118
Step 7: 2118 + 353 = 2471
Step 8: 2471 + 353 = 2824
Step 9: 2824 + 353 = 3177
Step 10: 3177 + 353 = 3530
Step 11: 3530 + 353 = 3883
Step 12: 3883 + 353 = 4236
Step 13: 4236 + 353 = 4589
Step 14: 4589 + 353 = 4942
Step 15: 4942 + 353 = 5295
Step 16: 5295 + 353 = 5648
Step 17: 5648 + 353 = 6001
Step 18: 6001 + 353 = 6354
Step 19: 6354 + 353 = 6707
Step 20: 6707 + 353 = 7060
Step 21: 7060 + 353 = 7413
Step 22: 7413 + 353 = 7766
Step 23: 7766 + 353 = 8119
Step 24: 8119 + 353 = 8472
Step 25: 8472 + 353 = 8825
Step 26: 8825 + 353 = 9178
Step 27: 9178 + 353 = 9531
Step 28: 9531 + 353 = 9884
Step 29: 9884 + 353 = 10237
Step 30: 10237 + 353 = 10590
Step 31: 10590 + 353 = 10943
Step 32: 10943 + 353 = 11296
Step 33: 11296 + 353 = 11649
Step 34: 11649 + 353 = 12002
Step 35: 12002 + 353 = 12355
Step 36: 12355 + 353 = 12708
Step 37: 12708 + 353 = 13061
Step 38: 13061 + 353 = 13414
Step 39: 13414 + 353 = 13767
Step 40: 13767 + 353 = 14120
Step 41: 14120 + 353 = 14473
Step 42: 14473 + 353 = 14826
Step 43: 14826 + 353 = 15179
Step 44: 15179 + 353 = 15532
Step 45: 15532 + 353 = 15885
Step 46: 15885 + 353 = 16238
Step 47: 16238 + 353 = 16591
Step 48: 16591 + 353 = 16944
Step 49: 16944 + 353 = 17297
Step 50: 17297 + 353 = 17650
Step 51: 17650 + 353 = 18003
Step 52: 18003 + 353 = 18356
Step 53: 18356 + 353 = 18709
Step 54: 18709 + 353 = 19062
Step 55: 19062 + 353 = 19415
Step 56: 19415 + 353 = 19768
Step 57: 19768 + 353 = 20121
Step 58: 20121 + 353 = 20474
Step 59: 20474 + 353 = 20827
Step 60: 20827 + 353 = 21180
Step 61: 21180 + 353 = 21533
Step 62: 21533 + 353 = 21886
Step 63: 21886 + 353 = 22239
Step 64: 22239 + 353 = 22592
Step 65: 22592 + 353 = 22945
Step 66: 22945 + 353 = 23298
Step 67: 23298 + 353 = 23651
Step 68: 23651 + 353 = 24004
Step 69: 24004 + 353 = 24357
Step 70: 24357 + 353 = 24710
Step 71: 24710 + 353 = 25063
Step 72: 25063 + 353 = 25416
Step 73: 25416 + 353 = 25769
Step 74: 25769 + 353 = 26122
Step 75: 26122 + 353 = 26475
Step 76: 26475 + 353 = 26828
Step 77: 26828 + 353 = 27181
Step 78: 27181 + 353 = 27534
Step 79: 27534 + 353 = 27887
Step 80: 27887 + 353 = 28240
Step 81: 28240 + 353 = 28593

So, 353*81 = 28593