OK, let's crack this. We're given 70 and our task is to multiply it by 86. Essentially, we'll be adding 70 to itself 86 times.
Step 1: 0 + 70 = 70
Step 2: 70 + 70 = 140
Step 3: 140 + 70 = 210
Step 4: 210 + 70 = 280
Step 5: 280 + 70 = 350
Step 6: 350 + 70 = 420
Step 7: 420 + 70 = 490
Step 8: 490 + 70 = 560
Step 9: 560 + 70 = 630
Step 10: 630 + 70 = 700
Step 11: 700 + 70 = 770
Step 12: 770 + 70 = 840
Step 13: 840 + 70 = 910
Step 14: 910 + 70 = 980
Step 15: 980 + 70 = 1050
Step 16: 1050 + 70 = 1120
Step 17: 1120 + 70 = 1190
Step 18: 1190 + 70 = 1260
Step 19: 1260 + 70 = 1330
Step 20: 1330 + 70 = 1400
Step 21: 1400 + 70 = 1470
Step 22: 1470 + 70 = 1540
Step 23: 1540 + 70 = 1610
Step 24: 1610 + 70 = 1680
Step 25: 1680 + 70 = 1750
Step 26: 1750 + 70 = 1820
Step 27: 1820 + 70 = 1890
Step 28: 1890 + 70 = 1960
Step 29: 1960 + 70 = 2030
Step 30: 2030 + 70 = 2100
Step 31: 2100 + 70 = 2170
Step 32: 2170 + 70 = 2240
Step 33: 2240 + 70 = 2310
Step 34: 2310 + 70 = 2380
Step 35: 2380 + 70 = 2450
Step 36: 2450 + 70 = 2520
Step 37: 2520 + 70 = 2590
Step 38: 2590 + 70 = 2660
Step 39: 2660 + 70 = 2730
Step 40: 2730 + 70 = 2800
Step 41: 2800 + 70 = 2870
Step 42: 2870 + 70 = 2940
Step 43: 2940 + 70 = 3010
Step 44: 3010 + 70 = 3080
Step 45: 3080 + 70 = 3150
Step 46: 3150 + 70 = 3220
Step 47: 3220 + 70 = 3290
Step 48: 3290 + 70 = 3360
Step 49: 3360 + 70 = 3430
Step 50: 3430 + 70 = 3500
Step 51: 3500 + 70 = 3570
Step 52: 3570 + 70 = 3640
Step 53: 3640 + 70 = 3710
Step 54: 3710 + 70 = 3780
Step 55: 3780 + 70 = 3850
Step 56: 3850 + 70 = 3920
Step 57: 3920 + 70 = 3990
Step 58: 3990 + 70 = 4060
Step 59: 4060 + 70 = 4130
Step 60: 4130 + 70 = 4200
Step 61: 4200 + 70 = 4270
Step 62: 4270 + 70 = 4340
Step 63: 4340 + 70 = 4410
Step 64: 4410 + 70 = 4480
Step 65: 4480 + 70 = 4550
Step 66: 4550 + 70 = 4620
Step 67: 4620 + 70 = 4690
Step 68: 4690 + 70 = 4760
Step 69: 4760 + 70 = 4830
Step 70: 4830 + 70 = 4900
Step 71: 4900 + 70 = 4970
Step 72: 4970 + 70 = 5040
Step 73: 5040 + 70 = 5110
Step 74: 5110 + 70 = 5180
Step 75: 5180 + 70 = 5250
Step 76: 5250 + 70 = 5320
Step 77: 5320 + 70 = 5390
Step 78: 5390 + 70 = 5460
Step 79: 5460 + 70 = 5530
Step 80: 5530 + 70 = 5600
Step 81: 5600 + 70 = 5670
Step 82: 5670 + 70 = 5740
Step 83: 5740 + 70 = 5810
Step 84: 5810 + 70 = 5880
Step 85: 5880 + 70 = 5950
Step 86: 5950 + 70 = 6020

So, 70*86 = 6020