Let's roll up our sleeves and solve this. We have 105 and we're going to multiply it by 43, essentially adding 105 to itself 43 times.
Step 1: 0 + 105 = 105
Step 2: 105 + 105 = 210
Step 3: 210 + 105 = 315
Step 4: 315 + 105 = 420
Step 5: 420 + 105 = 525
Step 6: 525 + 105 = 630
Step 7: 630 + 105 = 735
Step 8: 735 + 105 = 840
Step 9: 840 + 105 = 945
Step 10: 945 + 105 = 1050
Step 11: 1050 + 105 = 1155
Step 12: 1155 + 105 = 1260
Step 13: 1260 + 105 = 1365
Step 14: 1365 + 105 = 1470
Step 15: 1470 + 105 = 1575
Step 16: 1575 + 105 = 1680
Step 17: 1680 + 105 = 1785
Step 18: 1785 + 105 = 1890
Step 19: 1890 + 105 = 1995
Step 20: 1995 + 105 = 2100
Step 21: 2100 + 105 = 2205
Step 22: 2205 + 105 = 2310
Step 23: 2310 + 105 = 2415
Step 24: 2415 + 105 = 2520
Step 25: 2520 + 105 = 2625
Step 26: 2625 + 105 = 2730
Step 27: 2730 + 105 = 2835
Step 28: 2835 + 105 = 2940
Step 29: 2940 + 105 = 3045
Step 30: 3045 + 105 = 3150
Step 31: 3150 + 105 = 3255
Step 32: 3255 + 105 = 3360
Step 33: 3360 + 105 = 3465
Step 34: 3465 + 105 = 3570
Step 35: 3570 + 105 = 3675
Step 36: 3675 + 105 = 3780
Step 37: 3780 + 105 = 3885
Step 38: 3885 + 105 = 3990
Step 39: 3990 + 105 = 4095
Step 40: 4095 + 105 = 4200
Step 41: 4200 + 105 = 4305
Step 42: 4305 + 105 = 4410
Step 43: 4410 + 105 = 4515

So, 105*43 = 4515