Alright, let's solve this math problem step by step. First, we have the number 855. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 13. So, we're going to take the number 855 and add it to itself 13 times.
Step 1: 0 + 855 = 855
Step 2: 855 + 855 = 1710
Step 3: 1710 + 855 = 2565
Step 4: 2565 + 855 = 3420
Step 5: 3420 + 855 = 4275
Step 6: 4275 + 855 = 5130
Step 7: 5130 + 855 = 5985
Step 8: 5985 + 855 = 6840
Step 9: 6840 + 855 = 7695
Step 10: 7695 + 855 = 8550
Step 11: 8550 + 855 = 9405
Step 12: 9405 + 855 = 10260
Step 13: 10260 + 855 = 11115

So, 855*13 = 11115