OK, let's crack this. We're given 651 and our task is to multiply it by 4. Essentially, we'll be adding 651 to itself 4 times.
Step 1: 0 + 651 = 651
Step 2: 651 + 651 = 1302
Step 3: 1302 + 651 = 1953
Step 4: 1953 + 651 = 2604

So, 651*4 = 2604