Sure thing, let's get straight to it. We start with 342 and we're going to multiply it by 81, which means adding 342 to itself 81 times.
Step 1: 0 + 342 = 342
Step 2: 342 + 342 = 684
Step 3: 684 + 342 = 1026
Step 4: 1026 + 342 = 1368
Step 5: 1368 + 342 = 1710
Step 6: 1710 + 342 = 2052
Step 7: 2052 + 342 = 2394
Step 8: 2394 + 342 = 2736
Step 9: 2736 + 342 = 3078
Step 10: 3078 + 342 = 3420
Step 11: 3420 + 342 = 3762
Step 12: 3762 + 342 = 4104
Step 13: 4104 + 342 = 4446
Step 14: 4446 + 342 = 4788
Step 15: 4788 + 342 = 5130
Step 16: 5130 + 342 = 5472
Step 17: 5472 + 342 = 5814
Step 18: 5814 + 342 = 6156
Step 19: 6156 + 342 = 6498
Step 20: 6498 + 342 = 6840
Step 21: 6840 + 342 = 7182
Step 22: 7182 + 342 = 7524
Step 23: 7524 + 342 = 7866
Step 24: 7866 + 342 = 8208
Step 25: 8208 + 342 = 8550
Step 26: 8550 + 342 = 8892
Step 27: 8892 + 342 = 9234
Step 28: 9234 + 342 = 9576
Step 29: 9576 + 342 = 9918
Step 30: 9918 + 342 = 10260
Step 31: 10260 + 342 = 10602
Step 32: 10602 + 342 = 10944
Step 33: 10944 + 342 = 11286
Step 34: 11286 + 342 = 11628
Step 35: 11628 + 342 = 11970
Step 36: 11970 + 342 = 12312
Step 37: 12312 + 342 = 12654
Step 38: 12654 + 342 = 12996
Step 39: 12996 + 342 = 13338
Step 40: 13338 + 342 = 13680
Step 41: 13680 + 342 = 14022
Step 42: 14022 + 342 = 14364
Step 43: 14364 + 342 = 14706
Step 44: 14706 + 342 = 15048
Step 45: 15048 + 342 = 15390
Step 46: 15390 + 342 = 15732
Step 47: 15732 + 342 = 16074
Step 48: 16074 + 342 = 16416
Step 49: 16416 + 342 = 16758
Step 50: 16758 + 342 = 17100
Step 51: 17100 + 342 = 17442
Step 52: 17442 + 342 = 17784
Step 53: 17784 + 342 = 18126
Step 54: 18126 + 342 = 18468
Step 55: 18468 + 342 = 18810
Step 56: 18810 + 342 = 19152
Step 57: 19152 + 342 = 19494
Step 58: 19494 + 342 = 19836
Step 59: 19836 + 342 = 20178
Step 60: 20178 + 342 = 20520
Step 61: 20520 + 342 = 20862
Step 62: 20862 + 342 = 21204
Step 63: 21204 + 342 = 21546
Step 64: 21546 + 342 = 21888
Step 65: 21888 + 342 = 22230
Step 66: 22230 + 342 = 22572
Step 67: 22572 + 342 = 22914
Step 68: 22914 + 342 = 23256
Step 69: 23256 + 342 = 23598
Step 70: 23598 + 342 = 23940
Step 71: 23940 + 342 = 24282
Step 72: 24282 + 342 = 24624
Step 73: 24624 + 342 = 24966
Step 74: 24966 + 342 = 25308
Step 75: 25308 + 342 = 25650
Step 76: 25650 + 342 = 25992
Step 77: 25992 + 342 = 26334
Step 78: 26334 + 342 = 26676
Step 79: 26676 + 342 = 27018
Step 80: 27018 + 342 = 27360
Step 81: 27360 + 342 = 27702

So, 342*81 = 27702