Let's roll up our sleeves and solve this. We have 815 and we're going to multiply it by 3, essentially adding 815 to itself 3 times.
Step 1: 0 + 815 = 815
Step 2: 815 + 815 = 1630
Step 3: 1630 + 815 = 2445

So, 815*3 = 2445