OK, let's crack this. We're given 85 and our task is to multiply it by 66. Essentially, we'll be adding 85 to itself 66 times.
Step 1: 0 + 85 = 85
Step 2: 85 + 85 = 170
Step 3: 170 + 85 = 255
Step 4: 255 + 85 = 340
Step 5: 340 + 85 = 425
Step 6: 425 + 85 = 510
Step 7: 510 + 85 = 595
Step 8: 595 + 85 = 680
Step 9: 680 + 85 = 765
Step 10: 765 + 85 = 850
Step 11: 850 + 85 = 935
Step 12: 935 + 85 = 1020
Step 13: 1020 + 85 = 1105
Step 14: 1105 + 85 = 1190
Step 15: 1190 + 85 = 1275
Step 16: 1275 + 85 = 1360
Step 17: 1360 + 85 = 1445
Step 18: 1445 + 85 = 1530
Step 19: 1530 + 85 = 1615
Step 20: 1615 + 85 = 1700
Step 21: 1700 + 85 = 1785
Step 22: 1785 + 85 = 1870
Step 23: 1870 + 85 = 1955
Step 24: 1955 + 85 = 2040
Step 25: 2040 + 85 = 2125
Step 26: 2125 + 85 = 2210
Step 27: 2210 + 85 = 2295
Step 28: 2295 + 85 = 2380
Step 29: 2380 + 85 = 2465
Step 30: 2465 + 85 = 2550
Step 31: 2550 + 85 = 2635
Step 32: 2635 + 85 = 2720
Step 33: 2720 + 85 = 2805
Step 34: 2805 + 85 = 2890
Step 35: 2890 + 85 = 2975
Step 36: 2975 + 85 = 3060
Step 37: 3060 + 85 = 3145
Step 38: 3145 + 85 = 3230
Step 39: 3230 + 85 = 3315
Step 40: 3315 + 85 = 3400
Step 41: 3400 + 85 = 3485
Step 42: 3485 + 85 = 3570
Step 43: 3570 + 85 = 3655
Step 44: 3655 + 85 = 3740
Step 45: 3740 + 85 = 3825
Step 46: 3825 + 85 = 3910
Step 47: 3910 + 85 = 3995
Step 48: 3995 + 85 = 4080
Step 49: 4080 + 85 = 4165
Step 50: 4165 + 85 = 4250
Step 51: 4250 + 85 = 4335
Step 52: 4335 + 85 = 4420
Step 53: 4420 + 85 = 4505
Step 54: 4505 + 85 = 4590
Step 55: 4590 + 85 = 4675
Step 56: 4675 + 85 = 4760
Step 57: 4760 + 85 = 4845
Step 58: 4845 + 85 = 4930
Step 59: 4930 + 85 = 5015
Step 60: 5015 + 85 = 5100
Step 61: 5100 + 85 = 5185
Step 62: 5185 + 85 = 5270
Step 63: 5270 + 85 = 5355
Step 64: 5355 + 85 = 5440
Step 65: 5440 + 85 = 5525
Step 66: 5525 + 85 = 5610

So, 85*66 = 5610