Let's get this math done. We have 504 and we're going to multiply it by 13. This is the same as taking 504 and adding it to itself 13 times.
Step 1: 0 + 504 = 504
Step 2: 504 + 504 = 1008
Step 3: 1008 + 504 = 1512
Step 4: 1512 + 504 = 2016
Step 5: 2016 + 504 = 2520
Step 6: 2520 + 504 = 3024
Step 7: 3024 + 504 = 3528
Step 8: 3528 + 504 = 4032
Step 9: 4032 + 504 = 4536
Step 10: 4536 + 504 = 5040
Step 11: 5040 + 504 = 5544
Step 12: 5544 + 504 = 6048
Step 13: 6048 + 504 = 6552

So, 504*13 = 6552