Let's roll up our sleeves and solve this. We have 489 and we're going to multiply it by 84, essentially adding 489 to itself 84 times.
Step 1: 0 + 489 = 489
Step 2: 489 + 489 = 978
Step 3: 978 + 489 = 1467
Step 4: 1467 + 489 = 1956
Step 5: 1956 + 489 = 2445
Step 6: 2445 + 489 = 2934
Step 7: 2934 + 489 = 3423
Step 8: 3423 + 489 = 3912
Step 9: 3912 + 489 = 4401
Step 10: 4401 + 489 = 4890
Step 11: 4890 + 489 = 5379
Step 12: 5379 + 489 = 5868
Step 13: 5868 + 489 = 6357
Step 14: 6357 + 489 = 6846
Step 15: 6846 + 489 = 7335
Step 16: 7335 + 489 = 7824
Step 17: 7824 + 489 = 8313
Step 18: 8313 + 489 = 8802
Step 19: 8802 + 489 = 9291
Step 20: 9291 + 489 = 9780
Step 21: 9780 + 489 = 10269
Step 22: 10269 + 489 = 10758
Step 23: 10758 + 489 = 11247
Step 24: 11247 + 489 = 11736
Step 25: 11736 + 489 = 12225
Step 26: 12225 + 489 = 12714
Step 27: 12714 + 489 = 13203
Step 28: 13203 + 489 = 13692
Step 29: 13692 + 489 = 14181
Step 30: 14181 + 489 = 14670
Step 31: 14670 + 489 = 15159
Step 32: 15159 + 489 = 15648
Step 33: 15648 + 489 = 16137
Step 34: 16137 + 489 = 16626
Step 35: 16626 + 489 = 17115
Step 36: 17115 + 489 = 17604
Step 37: 17604 + 489 = 18093
Step 38: 18093 + 489 = 18582
Step 39: 18582 + 489 = 19071
Step 40: 19071 + 489 = 19560
Step 41: 19560 + 489 = 20049
Step 42: 20049 + 489 = 20538
Step 43: 20538 + 489 = 21027
Step 44: 21027 + 489 = 21516
Step 45: 21516 + 489 = 22005
Step 46: 22005 + 489 = 22494
Step 47: 22494 + 489 = 22983
Step 48: 22983 + 489 = 23472
Step 49: 23472 + 489 = 23961
Step 50: 23961 + 489 = 24450
Step 51: 24450 + 489 = 24939
Step 52: 24939 + 489 = 25428
Step 53: 25428 + 489 = 25917
Step 54: 25917 + 489 = 26406
Step 55: 26406 + 489 = 26895
Step 56: 26895 + 489 = 27384
Step 57: 27384 + 489 = 27873
Step 58: 27873 + 489 = 28362
Step 59: 28362 + 489 = 28851
Step 60: 28851 + 489 = 29340
Step 61: 29340 + 489 = 29829
Step 62: 29829 + 489 = 30318
Step 63: 30318 + 489 = 30807
Step 64: 30807 + 489 = 31296
Step 65: 31296 + 489 = 31785
Step 66: 31785 + 489 = 32274
Step 67: 32274 + 489 = 32763
Step 68: 32763 + 489 = 33252
Step 69: 33252 + 489 = 33741
Step 70: 33741 + 489 = 34230
Step 71: 34230 + 489 = 34719
Step 72: 34719 + 489 = 35208
Step 73: 35208 + 489 = 35697
Step 74: 35697 + 489 = 36186
Step 75: 36186 + 489 = 36675
Step 76: 36675 + 489 = 37164
Step 77: 37164 + 489 = 37653
Step 78: 37653 + 489 = 38142
Step 79: 38142 + 489 = 38631
Step 80: 38631 + 489 = 39120
Step 81: 39120 + 489 = 39609
Step 82: 39609 + 489 = 40098
Step 83: 40098 + 489 = 40587
Step 84: 40587 + 489 = 41076

So, 489*84 = 41076