Let's roll up our sleeves and solve this. We have 540 and we're going to multiply it by 4, essentially adding 540 to itself 4 times.
Step 1: 0 + 540 = 540
Step 2: 540 + 540 = 1080
Step 3: 1080 + 540 = 1620
Step 4: 1620 + 540 = 2160

So, 540*4 = 2160