OK, let's crack this. We're given 140 and our task is to multiply it by 108. Essentially, we'll be adding 140 to itself 108 times.
Step 1: 0 + 140 = 140
Step 2: 140 + 140 = 280
Step 3: 280 + 140 = 420
Step 4: 420 + 140 = 560
Step 5: 560 + 140 = 700
Step 6: 700 + 140 = 840
Step 7: 840 + 140 = 980
Step 8: 980 + 140 = 1120
Step 9: 1120 + 140 = 1260
Step 10: 1260 + 140 = 1400
Step 11: 1400 + 140 = 1540
Step 12: 1540 + 140 = 1680
Step 13: 1680 + 140 = 1820
Step 14: 1820 + 140 = 1960
Step 15: 1960 + 140 = 2100
Step 16: 2100 + 140 = 2240
Step 17: 2240 + 140 = 2380
Step 18: 2380 + 140 = 2520
Step 19: 2520 + 140 = 2660
Step 20: 2660 + 140 = 2800
Step 21: 2800 + 140 = 2940
Step 22: 2940 + 140 = 3080
Step 23: 3080 + 140 = 3220
Step 24: 3220 + 140 = 3360
Step 25: 3360 + 140 = 3500
Step 26: 3500 + 140 = 3640
Step 27: 3640 + 140 = 3780
Step 28: 3780 + 140 = 3920
Step 29: 3920 + 140 = 4060
Step 30: 4060 + 140 = 4200
Step 31: 4200 + 140 = 4340
Step 32: 4340 + 140 = 4480
Step 33: 4480 + 140 = 4620
Step 34: 4620 + 140 = 4760
Step 35: 4760 + 140 = 4900
Step 36: 4900 + 140 = 5040
Step 37: 5040 + 140 = 5180
Step 38: 5180 + 140 = 5320
Step 39: 5320 + 140 = 5460
Step 40: 5460 + 140 = 5600
Step 41: 5600 + 140 = 5740
Step 42: 5740 + 140 = 5880
Step 43: 5880 + 140 = 6020
Step 44: 6020 + 140 = 6160
Step 45: 6160 + 140 = 6300
Step 46: 6300 + 140 = 6440
Step 47: 6440 + 140 = 6580
Step 48: 6580 + 140 = 6720
Step 49: 6720 + 140 = 6860
Step 50: 6860 + 140 = 7000
Step 51: 7000 + 140 = 7140
Step 52: 7140 + 140 = 7280
Step 53: 7280 + 140 = 7420
Step 54: 7420 + 140 = 7560
Step 55: 7560 + 140 = 7700
Step 56: 7700 + 140 = 7840
Step 57: 7840 + 140 = 7980
Step 58: 7980 + 140 = 8120
Step 59: 8120 + 140 = 8260
Step 60: 8260 + 140 = 8400
Step 61: 8400 + 140 = 8540
Step 62: 8540 + 140 = 8680
Step 63: 8680 + 140 = 8820
Step 64: 8820 + 140 = 8960
Step 65: 8960 + 140 = 9100
Step 66: 9100 + 140 = 9240
Step 67: 9240 + 140 = 9380
Step 68: 9380 + 140 = 9520
Step 69: 9520 + 140 = 9660
Step 70: 9660 + 140 = 9800
Step 71: 9800 + 140 = 9940
Step 72: 9940 + 140 = 10080
Step 73: 10080 + 140 = 10220
Step 74: 10220 + 140 = 10360
Step 75: 10360 + 140 = 10500
Step 76: 10500 + 140 = 10640
Step 77: 10640 + 140 = 10780
Step 78: 10780 + 140 = 10920
Step 79: 10920 + 140 = 11060
Step 80: 11060 + 140 = 11200
Step 81: 11200 + 140 = 11340
Step 82: 11340 + 140 = 11480
Step 83: 11480 + 140 = 11620
Step 84: 11620 + 140 = 11760
Step 85: 11760 + 140 = 11900
Step 86: 11900 + 140 = 12040
Step 87: 12040 + 140 = 12180
Step 88: 12180 + 140 = 12320
Step 89: 12320 + 140 = 12460
Step 90: 12460 + 140 = 12600
Step 91: 12600 + 140 = 12740
Step 92: 12740 + 140 = 12880
Step 93: 12880 + 140 = 13020
Step 94: 13020 + 140 = 13160
Step 95: 13160 + 140 = 13300
Step 96: 13300 + 140 = 13440
Step 97: 13440 + 140 = 13580
Step 98: 13580 + 140 = 13720
Step 99: 13720 + 140 = 13860
Step 100: 13860 + 140 = 14000
Step 101: 14000 + 140 = 14140
Step 102: 14140 + 140 = 14280
Step 103: 14280 + 140 = 14420
Step 104: 14420 + 140 = 14560
Step 105: 14560 + 140 = 14700
Step 106: 14700 + 140 = 14840
Step 107: 14840 + 140 = 14980
Step 108: 14980 + 140 = 15120

So, 140*108 = 15120