OK, let's work through this together. We're starting with 505 and we're going to multiply it by 11, which means we add 505 to itself 11 times.
Step 1: 0 + 505 = 505
Step 2: 505 + 505 = 1010
Step 3: 1010 + 505 = 1515
Step 4: 1515 + 505 = 2020
Step 5: 2020 + 505 = 2525
Step 6: 2525 + 505 = 3030
Step 7: 3030 + 505 = 3535
Step 8: 3535 + 505 = 4040
Step 9: 4040 + 505 = 4545
Step 10: 4545 + 505 = 5050
Step 11: 5050 + 505 = 5555

So, 505*11 = 5555