Alright, let's solve this math problem step by step. First, we have the number 931. 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 931 and add it to itself 13 times.
Step 1: 0 + 931 = 931
Step 2: 931 + 931 = 1862
Step 3: 1862 + 931 = 2793
Step 4: 2793 + 931 = 3724
Step 5: 3724 + 931 = 4655
Step 6: 4655 + 931 = 5586
Step 7: 5586 + 931 = 6517
Step 8: 6517 + 931 = 7448
Step 9: 7448 + 931 = 8379
Step 10: 8379 + 931 = 9310
Step 11: 9310 + 931 = 10241
Step 12: 10241 + 931 = 11172
Step 13: 11172 + 931 = 12103

So, 931*13 = 12103