Let's get this math done. We have 64 and we're going to multiply it by 5. This is the same as taking 64 and adding it to itself 5 times.
Step 1: 0 + 64 = 64
Step 2: 64 + 64 = 128
Step 3: 128 + 64 = 192
Step 4: 192 + 64 = 256
Step 5: 256 + 64 = 320

So, 64*5 = 320