OK, let's work through this together. We're starting with 920 and we're going to multiply it by 89, which means we add 920 to itself 89 times.
Step 1: 0 + 920 = 920
Step 2: 920 + 920 = 1840
Step 3: 1840 + 920 = 2760
Step 4: 2760 + 920 = 3680
Step 5: 3680 + 920 = 4600
Step 6: 4600 + 920 = 5520
Step 7: 5520 + 920 = 6440
Step 8: 6440 + 920 = 7360
Step 9: 7360 + 920 = 8280
Step 10: 8280 + 920 = 9200
Step 11: 9200 + 920 = 10120
Step 12: 10120 + 920 = 11040
Step 13: 11040 + 920 = 11960
Step 14: 11960 + 920 = 12880
Step 15: 12880 + 920 = 13800
Step 16: 13800 + 920 = 14720
Step 17: 14720 + 920 = 15640
Step 18: 15640 + 920 = 16560
Step 19: 16560 + 920 = 17480
Step 20: 17480 + 920 = 18400
Step 21: 18400 + 920 = 19320
Step 22: 19320 + 920 = 20240
Step 23: 20240 + 920 = 21160
Step 24: 21160 + 920 = 22080
Step 25: 22080 + 920 = 23000
Step 26: 23000 + 920 = 23920
Step 27: 23920 + 920 = 24840
Step 28: 24840 + 920 = 25760
Step 29: 25760 + 920 = 26680
Step 30: 26680 + 920 = 27600
Step 31: 27600 + 920 = 28520
Step 32: 28520 + 920 = 29440
Step 33: 29440 + 920 = 30360
Step 34: 30360 + 920 = 31280
Step 35: 31280 + 920 = 32200
Step 36: 32200 + 920 = 33120
Step 37: 33120 + 920 = 34040
Step 38: 34040 + 920 = 34960
Step 39: 34960 + 920 = 35880
Step 40: 35880 + 920 = 36800
Step 41: 36800 + 920 = 37720
Step 42: 37720 + 920 = 38640
Step 43: 38640 + 920 = 39560
Step 44: 39560 + 920 = 40480
Step 45: 40480 + 920 = 41400
Step 46: 41400 + 920 = 42320
Step 47: 42320 + 920 = 43240
Step 48: 43240 + 920 = 44160
Step 49: 44160 + 920 = 45080
Step 50: 45080 + 920 = 46000
Step 51: 46000 + 920 = 46920
Step 52: 46920 + 920 = 47840
Step 53: 47840 + 920 = 48760
Step 54: 48760 + 920 = 49680
Step 55: 49680 + 920 = 50600
Step 56: 50600 + 920 = 51520
Step 57: 51520 + 920 = 52440
Step 58: 52440 + 920 = 53360
Step 59: 53360 + 920 = 54280
Step 60: 54280 + 920 = 55200
Step 61: 55200 + 920 = 56120
Step 62: 56120 + 920 = 57040
Step 63: 57040 + 920 = 57960
Step 64: 57960 + 920 = 58880
Step 65: 58880 + 920 = 59800
Step 66: 59800 + 920 = 60720
Step 67: 60720 + 920 = 61640
Step 68: 61640 + 920 = 62560
Step 69: 62560 + 920 = 63480
Step 70: 63480 + 920 = 64400
Step 71: 64400 + 920 = 65320
Step 72: 65320 + 920 = 66240
Step 73: 66240 + 920 = 67160
Step 74: 67160 + 920 = 68080
Step 75: 68080 + 920 = 69000
Step 76: 69000 + 920 = 69920
Step 77: 69920 + 920 = 70840
Step 78: 70840 + 920 = 71760
Step 79: 71760 + 920 = 72680
Step 80: 72680 + 920 = 73600
Step 81: 73600 + 920 = 74520
Step 82: 74520 + 920 = 75440
Step 83: 75440 + 920 = 76360
Step 84: 76360 + 920 = 77280
Step 85: 77280 + 920 = 78200
Step 86: 78200 + 920 = 79120
Step 87: 79120 + 920 = 80040
Step 88: 80040 + 920 = 80960
Step 89: 80960 + 920 = 81880

So, 920*89 = 81880