OK, let's crack this. We're given 907 and our task is to multiply it by 84. Essentially, we'll be adding 907 to itself 84 times.
Step 1: 0 + 907 = 907
Step 2: 907 + 907 = 1814
Step 3: 1814 + 907 = 2721
Step 4: 2721 + 907 = 3628
Step 5: 3628 + 907 = 4535
Step 6: 4535 + 907 = 5442
Step 7: 5442 + 907 = 6349
Step 8: 6349 + 907 = 7256
Step 9: 7256 + 907 = 8163
Step 10: 8163 + 907 = 9070
Step 11: 9070 + 907 = 9977
Step 12: 9977 + 907 = 10884
Step 13: 10884 + 907 = 11791
Step 14: 11791 + 907 = 12698
Step 15: 12698 + 907 = 13605
Step 16: 13605 + 907 = 14512
Step 17: 14512 + 907 = 15419
Step 18: 15419 + 907 = 16326
Step 19: 16326 + 907 = 17233
Step 20: 17233 + 907 = 18140
Step 21: 18140 + 907 = 19047
Step 22: 19047 + 907 = 19954
Step 23: 19954 + 907 = 20861
Step 24: 20861 + 907 = 21768
Step 25: 21768 + 907 = 22675
Step 26: 22675 + 907 = 23582
Step 27: 23582 + 907 = 24489
Step 28: 24489 + 907 = 25396
Step 29: 25396 + 907 = 26303
Step 30: 26303 + 907 = 27210
Step 31: 27210 + 907 = 28117
Step 32: 28117 + 907 = 29024
Step 33: 29024 + 907 = 29931
Step 34: 29931 + 907 = 30838
Step 35: 30838 + 907 = 31745
Step 36: 31745 + 907 = 32652
Step 37: 32652 + 907 = 33559
Step 38: 33559 + 907 = 34466
Step 39: 34466 + 907 = 35373
Step 40: 35373 + 907 = 36280
Step 41: 36280 + 907 = 37187
Step 42: 37187 + 907 = 38094
Step 43: 38094 + 907 = 39001
Step 44: 39001 + 907 = 39908
Step 45: 39908 + 907 = 40815
Step 46: 40815 + 907 = 41722
Step 47: 41722 + 907 = 42629
Step 48: 42629 + 907 = 43536
Step 49: 43536 + 907 = 44443
Step 50: 44443 + 907 = 45350
Step 51: 45350 + 907 = 46257
Step 52: 46257 + 907 = 47164
Step 53: 47164 + 907 = 48071
Step 54: 48071 + 907 = 48978
Step 55: 48978 + 907 = 49885
Step 56: 49885 + 907 = 50792
Step 57: 50792 + 907 = 51699
Step 58: 51699 + 907 = 52606
Step 59: 52606 + 907 = 53513
Step 60: 53513 + 907 = 54420
Step 61: 54420 + 907 = 55327
Step 62: 55327 + 907 = 56234
Step 63: 56234 + 907 = 57141
Step 64: 57141 + 907 = 58048
Step 65: 58048 + 907 = 58955
Step 66: 58955 + 907 = 59862
Step 67: 59862 + 907 = 60769
Step 68: 60769 + 907 = 61676
Step 69: 61676 + 907 = 62583
Step 70: 62583 + 907 = 63490
Step 71: 63490 + 907 = 64397
Step 72: 64397 + 907 = 65304
Step 73: 65304 + 907 = 66211
Step 74: 66211 + 907 = 67118
Step 75: 67118 + 907 = 68025
Step 76: 68025 + 907 = 68932
Step 77: 68932 + 907 = 69839
Step 78: 69839 + 907 = 70746
Step 79: 70746 + 907 = 71653
Step 80: 71653 + 907 = 72560
Step 81: 72560 + 907 = 73467
Step 82: 73467 + 907 = 74374
Step 83: 74374 + 907 = 75281
Step 84: 75281 + 907 = 76188

So, 907*84 = 76188