OK, let's crack this. We're given 503 and our task is to multiply it by 5. Essentially, we'll be adding 503 to itself 5 times.
Step 1: 0 + 503 = 503
Step 2: 503 + 503 = 1006
Step 3: 1006 + 503 = 1509
Step 4: 1509 + 503 = 2012
Step 5: 2012 + 503 = 2515

So, 503*5 = 2515