Let's get this math done. We have 819 and we're going to multiply it by 5. This is the same as taking 819 and adding it to itself 5 times.
Step 1: 0 + 819 = 819
Step 2: 819 + 819 = 1638
Step 3: 1638 + 819 = 2457
Step 4: 2457 + 819 = 3276
Step 5: 3276 + 819 = 4095

So, 819*5 = 4095