OK, let's work through this together. We're starting with 690 and we're going to multiply it by 128, which means we add 690 to itself 128 times.
Step 1: 0 + 690 = 690
Step 2: 690 + 690 = 1380
Step 3: 1380 + 690 = 2070
Step 4: 2070 + 690 = 2760
Step 5: 2760 + 690 = 3450
Step 6: 3450 + 690 = 4140
Step 7: 4140 + 690 = 4830
Step 8: 4830 + 690 = 5520
Step 9: 5520 + 690 = 6210
Step 10: 6210 + 690 = 6900
Step 11: 6900 + 690 = 7590
Step 12: 7590 + 690 = 8280
Step 13: 8280 + 690 = 8970
Step 14: 8970 + 690 = 9660
Step 15: 9660 + 690 = 10350
Step 16: 10350 + 690 = 11040
Step 17: 11040 + 690 = 11730
Step 18: 11730 + 690 = 12420
Step 19: 12420 + 690 = 13110
Step 20: 13110 + 690 = 13800
Step 21: 13800 + 690 = 14490
Step 22: 14490 + 690 = 15180
Step 23: 15180 + 690 = 15870
Step 24: 15870 + 690 = 16560
Step 25: 16560 + 690 = 17250
Step 26: 17250 + 690 = 17940
Step 27: 17940 + 690 = 18630
Step 28: 18630 + 690 = 19320
Step 29: 19320 + 690 = 20010
Step 30: 20010 + 690 = 20700
Step 31: 20700 + 690 = 21390
Step 32: 21390 + 690 = 22080
Step 33: 22080 + 690 = 22770
Step 34: 22770 + 690 = 23460
Step 35: 23460 + 690 = 24150
Step 36: 24150 + 690 = 24840
Step 37: 24840 + 690 = 25530
Step 38: 25530 + 690 = 26220
Step 39: 26220 + 690 = 26910
Step 40: 26910 + 690 = 27600
Step 41: 27600 + 690 = 28290
Step 42: 28290 + 690 = 28980
Step 43: 28980 + 690 = 29670
Step 44: 29670 + 690 = 30360
Step 45: 30360 + 690 = 31050
Step 46: 31050 + 690 = 31740
Step 47: 31740 + 690 = 32430
Step 48: 32430 + 690 = 33120
Step 49: 33120 + 690 = 33810
Step 50: 33810 + 690 = 34500
Step 51: 34500 + 690 = 35190
Step 52: 35190 + 690 = 35880
Step 53: 35880 + 690 = 36570
Step 54: 36570 + 690 = 37260
Step 55: 37260 + 690 = 37950
Step 56: 37950 + 690 = 38640
Step 57: 38640 + 690 = 39330
Step 58: 39330 + 690 = 40020
Step 59: 40020 + 690 = 40710
Step 60: 40710 + 690 = 41400
Step 61: 41400 + 690 = 42090
Step 62: 42090 + 690 = 42780
Step 63: 42780 + 690 = 43470
Step 64: 43470 + 690 = 44160
Step 65: 44160 + 690 = 44850
Step 66: 44850 + 690 = 45540
Step 67: 45540 + 690 = 46230
Step 68: 46230 + 690 = 46920
Step 69: 46920 + 690 = 47610
Step 70: 47610 + 690 = 48300
Step 71: 48300 + 690 = 48990
Step 72: 48990 + 690 = 49680
Step 73: 49680 + 690 = 50370
Step 74: 50370 + 690 = 51060
Step 75: 51060 + 690 = 51750
Step 76: 51750 + 690 = 52440
Step 77: 52440 + 690 = 53130
Step 78: 53130 + 690 = 53820
Step 79: 53820 + 690 = 54510
Step 80: 54510 + 690 = 55200
Step 81: 55200 + 690 = 55890
Step 82: 55890 + 690 = 56580
Step 83: 56580 + 690 = 57270
Step 84: 57270 + 690 = 57960
Step 85: 57960 + 690 = 58650
Step 86: 58650 + 690 = 59340
Step 87: 59340 + 690 = 60030
Step 88: 60030 + 690 = 60720
Step 89: 60720 + 690 = 61410
Step 90: 61410 + 690 = 62100
Step 91: 62100 + 690 = 62790
Step 92: 62790 + 690 = 63480
Step 93: 63480 + 690 = 64170
Step 94: 64170 + 690 = 64860
Step 95: 64860 + 690 = 65550
Step 96: 65550 + 690 = 66240
Step 97: 66240 + 690 = 66930
Step 98: 66930 + 690 = 67620
Step 99: 67620 + 690 = 68310
Step 100: 68310 + 690 = 69000
Step 101: 69000 + 690 = 69690
Step 102: 69690 + 690 = 70380
Step 103: 70380 + 690 = 71070
Step 104: 71070 + 690 = 71760
Step 105: 71760 + 690 = 72450
Step 106: 72450 + 690 = 73140
Step 107: 73140 + 690 = 73830
Step 108: 73830 + 690 = 74520
Step 109: 74520 + 690 = 75210
Step 110: 75210 + 690 = 75900
Step 111: 75900 + 690 = 76590
Step 112: 76590 + 690 = 77280
Step 113: 77280 + 690 = 77970
Step 114: 77970 + 690 = 78660
Step 115: 78660 + 690 = 79350
Step 116: 79350 + 690 = 80040
Step 117: 80040 + 690 = 80730
Step 118: 80730 + 690 = 81420
Step 119: 81420 + 690 = 82110
Step 120: 82110 + 690 = 82800
Step 121: 82800 + 690 = 83490
Step 122: 83490 + 690 = 84180
Step 123: 84180 + 690 = 84870
Step 124: 84870 + 690 = 85560
Step 125: 85560 + 690 = 86250
Step 126: 86250 + 690 = 86940
Step 127: 86940 + 690 = 87630
Step 128: 87630 + 690 = 88320

So, 690*128 = 88320