OK, let's crack this. We're given 5 and our task is to multiply it by 4. Essentially, we'll be adding 5 to itself 4 times.
Step 1: 0 + 5 = 5
Step 2: 5 + 5 = 10
Step 3: 10 + 5 = 15
Step 4: 15 + 5 = 20

So, 5*4 = 20