Let's roll up our sleeves and solve this. We have 664 and we're going to multiply it by 4, essentially adding 664 to itself 4 times.
Step 1: 0 + 664 = 664
Step 2: 664 + 664 = 1328
Step 3: 1328 + 664 = 1992
Step 4: 1992 + 664 = 2656

So, 664*4 = 2656