Let's roll up our sleeves and solve this. We have 636 and we're going to multiply it by 3, essentially adding 636 to itself 3 times.
Step 1: 0 + 636 = 636
Step 2: 636 + 636 = 1272
Step 3: 1272 + 636 = 1908

So, 636*3 = 1908