Alright, let's solve this math problem step by step. First, we have the number 504. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 20. So, we're going to take the number 504 and add it to itself 20 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
Step 16: 7560 + 504 = 8064
Step 17: 8064 + 504 = 8568
Step 18: 8568 + 504 = 9072
Step 19: 9072 + 504 = 9576
Step 20: 9576 + 504 = 10080

So, 504*20 = 10080