Alright, let's solve this math problem step by step. First, we have the number 638. 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 638 and add it to itself 13 times.
Step 1: 0 + 638 = 638
Step 2: 638 + 638 = 1276
Step 3: 1276 + 638 = 1914
Step 4: 1914 + 638 = 2552
Step 5: 2552 + 638 = 3190
Step 6: 3190 + 638 = 3828
Step 7: 3828 + 638 = 4466
Step 8: 4466 + 638 = 5104
Step 9: 5104 + 638 = 5742
Step 10: 5742 + 638 = 6380
Step 11: 6380 + 638 = 7018
Step 12: 7018 + 638 = 7656
Step 13: 7656 + 638 = 8294

So, 638*13 = 8294