OK, let's crack this. We're given 684 and our task is to multiply it by 4. Essentially, we'll be adding 684 to itself 4 times.
Step 1: 0 + 684 = 684
Step 2: 684 + 684 = 1368
Step 3: 1368 + 684 = 2052
Step 4: 2052 + 684 = 2736

So, 684*4 = 2736