OK, let's work through this together. We're starting with 835 and we're going to multiply it by 105, which means we add 835 to itself 105 times.
Step 1: 0 + 835 = 835
Step 2: 835 + 835 = 1670
Step 3: 1670 + 835 = 2505
Step 4: 2505 + 835 = 3340
Step 5: 3340 + 835 = 4175
Step 6: 4175 + 835 = 5010
Step 7: 5010 + 835 = 5845
Step 8: 5845 + 835 = 6680
Step 9: 6680 + 835 = 7515
Step 10: 7515 + 835 = 8350
Step 11: 8350 + 835 = 9185
Step 12: 9185 + 835 = 10020
Step 13: 10020 + 835 = 10855
Step 14: 10855 + 835 = 11690
Step 15: 11690 + 835 = 12525
Step 16: 12525 + 835 = 13360
Step 17: 13360 + 835 = 14195
Step 18: 14195 + 835 = 15030
Step 19: 15030 + 835 = 15865
Step 20: 15865 + 835 = 16700
Step 21: 16700 + 835 = 17535
Step 22: 17535 + 835 = 18370
Step 23: 18370 + 835 = 19205
Step 24: 19205 + 835 = 20040
Step 25: 20040 + 835 = 20875
Step 26: 20875 + 835 = 21710
Step 27: 21710 + 835 = 22545
Step 28: 22545 + 835 = 23380
Step 29: 23380 + 835 = 24215
Step 30: 24215 + 835 = 25050
Step 31: 25050 + 835 = 25885
Step 32: 25885 + 835 = 26720
Step 33: 26720 + 835 = 27555
Step 34: 27555 + 835 = 28390
Step 35: 28390 + 835 = 29225
Step 36: 29225 + 835 = 30060
Step 37: 30060 + 835 = 30895
Step 38: 30895 + 835 = 31730
Step 39: 31730 + 835 = 32565
Step 40: 32565 + 835 = 33400
Step 41: 33400 + 835 = 34235
Step 42: 34235 + 835 = 35070
Step 43: 35070 + 835 = 35905
Step 44: 35905 + 835 = 36740
Step 45: 36740 + 835 = 37575
Step 46: 37575 + 835 = 38410
Step 47: 38410 + 835 = 39245
Step 48: 39245 + 835 = 40080
Step 49: 40080 + 835 = 40915
Step 50: 40915 + 835 = 41750
Step 51: 41750 + 835 = 42585
Step 52: 42585 + 835 = 43420
Step 53: 43420 + 835 = 44255
Step 54: 44255 + 835 = 45090
Step 55: 45090 + 835 = 45925
Step 56: 45925 + 835 = 46760
Step 57: 46760 + 835 = 47595
Step 58: 47595 + 835 = 48430
Step 59: 48430 + 835 = 49265
Step 60: 49265 + 835 = 50100
Step 61: 50100 + 835 = 50935
Step 62: 50935 + 835 = 51770
Step 63: 51770 + 835 = 52605
Step 64: 52605 + 835 = 53440
Step 65: 53440 + 835 = 54275
Step 66: 54275 + 835 = 55110
Step 67: 55110 + 835 = 55945
Step 68: 55945 + 835 = 56780
Step 69: 56780 + 835 = 57615
Step 70: 57615 + 835 = 58450
Step 71: 58450 + 835 = 59285
Step 72: 59285 + 835 = 60120
Step 73: 60120 + 835 = 60955
Step 74: 60955 + 835 = 61790
Step 75: 61790 + 835 = 62625
Step 76: 62625 + 835 = 63460
Step 77: 63460 + 835 = 64295
Step 78: 64295 + 835 = 65130
Step 79: 65130 + 835 = 65965
Step 80: 65965 + 835 = 66800
Step 81: 66800 + 835 = 67635
Step 82: 67635 + 835 = 68470
Step 83: 68470 + 835 = 69305
Step 84: 69305 + 835 = 70140
Step 85: 70140 + 835 = 70975
Step 86: 70975 + 835 = 71810
Step 87: 71810 + 835 = 72645
Step 88: 72645 + 835 = 73480
Step 89: 73480 + 835 = 74315
Step 90: 74315 + 835 = 75150
Step 91: 75150 + 835 = 75985
Step 92: 75985 + 835 = 76820
Step 93: 76820 + 835 = 77655
Step 94: 77655 + 835 = 78490
Step 95: 78490 + 835 = 79325
Step 96: 79325 + 835 = 80160
Step 97: 80160 + 835 = 80995
Step 98: 80995 + 835 = 81830
Step 99: 81830 + 835 = 82665
Step 100: 82665 + 835 = 83500
Step 101: 83500 + 835 = 84335
Step 102: 84335 + 835 = 85170
Step 103: 85170 + 835 = 86005
Step 104: 86005 + 835 = 86840
Step 105: 86840 + 835 = 87675

So, 835*105 = 87675