Let's get this math done. We have 345 and we're going to multiply it by 4. This is the same as taking 345 and adding it to itself 4 times.
Step 1: 0 + 345 = 345
Step 2: 345 + 345 = 690
Step 3: 690 + 345 = 1035
Step 4: 1035 + 345 = 1380

So, 345*4 = 1380