OK, let's work through this together. We're starting with 681 and we're going to multiply it by 4, which means we add 681 to itself 4 times.
Step 1: 0 + 681 = 681
Step 2: 681 + 681 = 1362
Step 3: 1362 + 681 = 2043
Step 4: 2043 + 681 = 2724

So, 681*4 = 2724