Let's get this math done. We have 825 and we're going to multiply it by 121. This is the same as taking 825 and adding it to itself 121 times.
Step 1: 0 + 825 = 825
Step 2: 825 + 825 = 1650
Step 3: 1650 + 825 = 2475
Step 4: 2475 + 825 = 3300
Step 5: 3300 + 825 = 4125
Step 6: 4125 + 825 = 4950
Step 7: 4950 + 825 = 5775
Step 8: 5775 + 825 = 6600
Step 9: 6600 + 825 = 7425
Step 10: 7425 + 825 = 8250
Step 11: 8250 + 825 = 9075
Step 12: 9075 + 825 = 9900
Step 13: 9900 + 825 = 10725
Step 14: 10725 + 825 = 11550
Step 15: 11550 + 825 = 12375
Step 16: 12375 + 825 = 13200
Step 17: 13200 + 825 = 14025
Step 18: 14025 + 825 = 14850
Step 19: 14850 + 825 = 15675
Step 20: 15675 + 825 = 16500
Step 21: 16500 + 825 = 17325
Step 22: 17325 + 825 = 18150
Step 23: 18150 + 825 = 18975
Step 24: 18975 + 825 = 19800
Step 25: 19800 + 825 = 20625
Step 26: 20625 + 825 = 21450
Step 27: 21450 + 825 = 22275
Step 28: 22275 + 825 = 23100
Step 29: 23100 + 825 = 23925
Step 30: 23925 + 825 = 24750
Step 31: 24750 + 825 = 25575
Step 32: 25575 + 825 = 26400
Step 33: 26400 + 825 = 27225
Step 34: 27225 + 825 = 28050
Step 35: 28050 + 825 = 28875
Step 36: 28875 + 825 = 29700
Step 37: 29700 + 825 = 30525
Step 38: 30525 + 825 = 31350
Step 39: 31350 + 825 = 32175
Step 40: 32175 + 825 = 33000
Step 41: 33000 + 825 = 33825
Step 42: 33825 + 825 = 34650
Step 43: 34650 + 825 = 35475
Step 44: 35475 + 825 = 36300
Step 45: 36300 + 825 = 37125
Step 46: 37125 + 825 = 37950
Step 47: 37950 + 825 = 38775
Step 48: 38775 + 825 = 39600
Step 49: 39600 + 825 = 40425
Step 50: 40425 + 825 = 41250
Step 51: 41250 + 825 = 42075
Step 52: 42075 + 825 = 42900
Step 53: 42900 + 825 = 43725
Step 54: 43725 + 825 = 44550
Step 55: 44550 + 825 = 45375
Step 56: 45375 + 825 = 46200
Step 57: 46200 + 825 = 47025
Step 58: 47025 + 825 = 47850
Step 59: 47850 + 825 = 48675
Step 60: 48675 + 825 = 49500
Step 61: 49500 + 825 = 50325
Step 62: 50325 + 825 = 51150
Step 63: 51150 + 825 = 51975
Step 64: 51975 + 825 = 52800
Step 65: 52800 + 825 = 53625
Step 66: 53625 + 825 = 54450
Step 67: 54450 + 825 = 55275
Step 68: 55275 + 825 = 56100
Step 69: 56100 + 825 = 56925
Step 70: 56925 + 825 = 57750
Step 71: 57750 + 825 = 58575
Step 72: 58575 + 825 = 59400
Step 73: 59400 + 825 = 60225
Step 74: 60225 + 825 = 61050
Step 75: 61050 + 825 = 61875
Step 76: 61875 + 825 = 62700
Step 77: 62700 + 825 = 63525
Step 78: 63525 + 825 = 64350
Step 79: 64350 + 825 = 65175
Step 80: 65175 + 825 = 66000
Step 81: 66000 + 825 = 66825
Step 82: 66825 + 825 = 67650
Step 83: 67650 + 825 = 68475
Step 84: 68475 + 825 = 69300
Step 85: 69300 + 825 = 70125
Step 86: 70125 + 825 = 70950
Step 87: 70950 + 825 = 71775
Step 88: 71775 + 825 = 72600
Step 89: 72600 + 825 = 73425
Step 90: 73425 + 825 = 74250
Step 91: 74250 + 825 = 75075
Step 92: 75075 + 825 = 75900
Step 93: 75900 + 825 = 76725
Step 94: 76725 + 825 = 77550
Step 95: 77550 + 825 = 78375
Step 96: 78375 + 825 = 79200
Step 97: 79200 + 825 = 80025
Step 98: 80025 + 825 = 80850
Step 99: 80850 + 825 = 81675
Step 100: 81675 + 825 = 82500
Step 101: 82500 + 825 = 83325
Step 102: 83325 + 825 = 84150
Step 103: 84150 + 825 = 84975
Step 104: 84975 + 825 = 85800
Step 105: 85800 + 825 = 86625
Step 106: 86625 + 825 = 87450
Step 107: 87450 + 825 = 88275
Step 108: 88275 + 825 = 89100
Step 109: 89100 + 825 = 89925
Step 110: 89925 + 825 = 90750
Step 111: 90750 + 825 = 91575
Step 112: 91575 + 825 = 92400
Step 113: 92400 + 825 = 93225
Step 114: 93225 + 825 = 94050
Step 115: 94050 + 825 = 94875
Step 116: 94875 + 825 = 95700
Step 117: 95700 + 825 = 96525
Step 118: 96525 + 825 = 97350
Step 119: 97350 + 825 = 98175
Step 120: 98175 + 825 = 99000
Step 121: 99000 + 825 = 99825

So, 825*121 = 99825