Let's get this math done. We have 878 and we're going to multiply it by 4. This is the same as taking 878 and adding it to itself 4 times.
Step 1: 0 + 878 = 878
Step 2: 878 + 878 = 1756
Step 3: 1756 + 878 = 2634
Step 4: 2634 + 878 = 3512

So, 878*4 = 3512