OK, let's work through this together. We're starting with 504 and we're going to multiply it by 5, which means we add 504 to itself 5 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

So, 504*5 = 2520