Sure thing, let's get straight to it. We start with 789 and we're going to multiply it by 85, which means adding 789 to itself 85 times.
Step 1: 0 + 789 = 789
Step 2: 789 + 789 = 1578
Step 3: 1578 + 789 = 2367
Step 4: 2367 + 789 = 3156
Step 5: 3156 + 789 = 3945
Step 6: 3945 + 789 = 4734
Step 7: 4734 + 789 = 5523
Step 8: 5523 + 789 = 6312
Step 9: 6312 + 789 = 7101
Step 10: 7101 + 789 = 7890
Step 11: 7890 + 789 = 8679
Step 12: 8679 + 789 = 9468
Step 13: 9468 + 789 = 10257
Step 14: 10257 + 789 = 11046
Step 15: 11046 + 789 = 11835
Step 16: 11835 + 789 = 12624
Step 17: 12624 + 789 = 13413
Step 18: 13413 + 789 = 14202
Step 19: 14202 + 789 = 14991
Step 20: 14991 + 789 = 15780
Step 21: 15780 + 789 = 16569
Step 22: 16569 + 789 = 17358
Step 23: 17358 + 789 = 18147
Step 24: 18147 + 789 = 18936
Step 25: 18936 + 789 = 19725
Step 26: 19725 + 789 = 20514
Step 27: 20514 + 789 = 21303
Step 28: 21303 + 789 = 22092
Step 29: 22092 + 789 = 22881
Step 30: 22881 + 789 = 23670
Step 31: 23670 + 789 = 24459
Step 32: 24459 + 789 = 25248
Step 33: 25248 + 789 = 26037
Step 34: 26037 + 789 = 26826
Step 35: 26826 + 789 = 27615
Step 36: 27615 + 789 = 28404
Step 37: 28404 + 789 = 29193
Step 38: 29193 + 789 = 29982
Step 39: 29982 + 789 = 30771
Step 40: 30771 + 789 = 31560
Step 41: 31560 + 789 = 32349
Step 42: 32349 + 789 = 33138
Step 43: 33138 + 789 = 33927
Step 44: 33927 + 789 = 34716
Step 45: 34716 + 789 = 35505
Step 46: 35505 + 789 = 36294
Step 47: 36294 + 789 = 37083
Step 48: 37083 + 789 = 37872
Step 49: 37872 + 789 = 38661
Step 50: 38661 + 789 = 39450
Step 51: 39450 + 789 = 40239
Step 52: 40239 + 789 = 41028
Step 53: 41028 + 789 = 41817
Step 54: 41817 + 789 = 42606
Step 55: 42606 + 789 = 43395
Step 56: 43395 + 789 = 44184
Step 57: 44184 + 789 = 44973
Step 58: 44973 + 789 = 45762
Step 59: 45762 + 789 = 46551
Step 60: 46551 + 789 = 47340
Step 61: 47340 + 789 = 48129
Step 62: 48129 + 789 = 48918
Step 63: 48918 + 789 = 49707
Step 64: 49707 + 789 = 50496
Step 65: 50496 + 789 = 51285
Step 66: 51285 + 789 = 52074
Step 67: 52074 + 789 = 52863
Step 68: 52863 + 789 = 53652
Step 69: 53652 + 789 = 54441
Step 70: 54441 + 789 = 55230
Step 71: 55230 + 789 = 56019
Step 72: 56019 + 789 = 56808
Step 73: 56808 + 789 = 57597
Step 74: 57597 + 789 = 58386
Step 75: 58386 + 789 = 59175
Step 76: 59175 + 789 = 59964
Step 77: 59964 + 789 = 60753
Step 78: 60753 + 789 = 61542
Step 79: 61542 + 789 = 62331
Step 80: 62331 + 789 = 63120
Step 81: 63120 + 789 = 63909
Step 82: 63909 + 789 = 64698
Step 83: 64698 + 789 = 65487
Step 84: 65487 + 789 = 66276
Step 85: 66276 + 789 = 67065

So, 789*85 = 67065