OK, let's crack this. We're given 873 and our task is to multiply it by 4. Essentially, we'll be adding 873 to itself 4 times.
Step 1: 0 + 873 = 873
Step 2: 873 + 873 = 1746
Step 3: 1746 + 873 = 2619
Step 4: 2619 + 873 = 3492

So, 873*4 = 3492