Let's roll up our sleeves and solve this. We have 168 and we're going to multiply it by 4, essentially adding 168 to itself 4 times.
Step 1: 0 + 168 = 168
Step 2: 168 + 168 = 336
Step 3: 336 + 168 = 504
Step 4: 504 + 168 = 672

So, 168*4 = 672