Let's roll up our sleeves and solve this. We have 816 and we're going to multiply it by 5, essentially adding 816 to itself 5 times.
Step 1: 0 + 816 = 816
Step 2: 816 + 816 = 1632
Step 3: 1632 + 816 = 2448
Step 4: 2448 + 816 = 3264
Step 5: 3264 + 816 = 4080

So, 816*5 = 4080