Without delay, let's solve this. We've got 850 and we will be multiplying it by 13, that is, adding 850 to itself 13 times.
Step 1: 0 + 850 = 850
Step 2: 850 + 850 = 1700
Step 3: 1700 + 850 = 2550
Step 4: 2550 + 850 = 3400
Step 5: 3400 + 850 = 4250
Step 6: 4250 + 850 = 5100
Step 7: 5100 + 850 = 5950
Step 8: 5950 + 850 = 6800
Step 9: 6800 + 850 = 7650
Step 10: 7650 + 850 = 8500
Step 11: 8500 + 850 = 9350
Step 12: 9350 + 850 = 10200
Step 13: 10200 + 850 = 11050

So, 850*13 = 11050