OK, let's crack this. We're given 170 and our task is to multiply it by 86. Essentially, we'll be adding 170 to itself 86 times.
Step 1: 0 + 170 = 170
Step 2: 170 + 170 = 340
Step 3: 340 + 170 = 510
Step 4: 510 + 170 = 680
Step 5: 680 + 170 = 850
Step 6: 850 + 170 = 1020
Step 7: 1020 + 170 = 1190
Step 8: 1190 + 170 = 1360
Step 9: 1360 + 170 = 1530
Step 10: 1530 + 170 = 1700
Step 11: 1700 + 170 = 1870
Step 12: 1870 + 170 = 2040
Step 13: 2040 + 170 = 2210
Step 14: 2210 + 170 = 2380
Step 15: 2380 + 170 = 2550
Step 16: 2550 + 170 = 2720
Step 17: 2720 + 170 = 2890
Step 18: 2890 + 170 = 3060
Step 19: 3060 + 170 = 3230
Step 20: 3230 + 170 = 3400
Step 21: 3400 + 170 = 3570
Step 22: 3570 + 170 = 3740
Step 23: 3740 + 170 = 3910
Step 24: 3910 + 170 = 4080
Step 25: 4080 + 170 = 4250
Step 26: 4250 + 170 = 4420
Step 27: 4420 + 170 = 4590
Step 28: 4590 + 170 = 4760
Step 29: 4760 + 170 = 4930
Step 30: 4930 + 170 = 5100
Step 31: 5100 + 170 = 5270
Step 32: 5270 + 170 = 5440
Step 33: 5440 + 170 = 5610
Step 34: 5610 + 170 = 5780
Step 35: 5780 + 170 = 5950
Step 36: 5950 + 170 = 6120
Step 37: 6120 + 170 = 6290
Step 38: 6290 + 170 = 6460
Step 39: 6460 + 170 = 6630
Step 40: 6630 + 170 = 6800
Step 41: 6800 + 170 = 6970
Step 42: 6970 + 170 = 7140
Step 43: 7140 + 170 = 7310
Step 44: 7310 + 170 = 7480
Step 45: 7480 + 170 = 7650
Step 46: 7650 + 170 = 7820
Step 47: 7820 + 170 = 7990
Step 48: 7990 + 170 = 8160
Step 49: 8160 + 170 = 8330
Step 50: 8330 + 170 = 8500
Step 51: 8500 + 170 = 8670
Step 52: 8670 + 170 = 8840
Step 53: 8840 + 170 = 9010
Step 54: 9010 + 170 = 9180
Step 55: 9180 + 170 = 9350
Step 56: 9350 + 170 = 9520
Step 57: 9520 + 170 = 9690
Step 58: 9690 + 170 = 9860
Step 59: 9860 + 170 = 10030
Step 60: 10030 + 170 = 10200
Step 61: 10200 + 170 = 10370
Step 62: 10370 + 170 = 10540
Step 63: 10540 + 170 = 10710
Step 64: 10710 + 170 = 10880
Step 65: 10880 + 170 = 11050
Step 66: 11050 + 170 = 11220
Step 67: 11220 + 170 = 11390
Step 68: 11390 + 170 = 11560
Step 69: 11560 + 170 = 11730
Step 70: 11730 + 170 = 11900
Step 71: 11900 + 170 = 12070
Step 72: 12070 + 170 = 12240
Step 73: 12240 + 170 = 12410
Step 74: 12410 + 170 = 12580
Step 75: 12580 + 170 = 12750
Step 76: 12750 + 170 = 12920
Step 77: 12920 + 170 = 13090
Step 78: 13090 + 170 = 13260
Step 79: 13260 + 170 = 13430
Step 80: 13430 + 170 = 13600
Step 81: 13600 + 170 = 13770
Step 82: 13770 + 170 = 13940
Step 83: 13940 + 170 = 14110
Step 84: 14110 + 170 = 14280
Step 85: 14280 + 170 = 14450
Step 86: 14450 + 170 = 14620

So, 170*86 = 14620