Sure thing! We've got 504 and we're gonna multiply it by 15. That's the same as adding 504 to itself 15 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
Step 14: 6552 + 504 = 7056
Step 15: 7056 + 504 = 7560

So, 504*15 = 7560