OK, let's work through this together. We're starting with 678 and we're going to multiply it by 4, which means we add 678 to itself 4 times.
Step 1: 0 + 678 = 678
Step 2: 678 + 678 = 1356
Step 3: 1356 + 678 = 2034
Step 4: 2034 + 678 = 2712

So, 678*4 = 2712