OK, let's crack this. We're given 852 and our task is to multiply it by 3. Essentially, we'll be adding 852 to itself 3 times.
Step 1: 0 + 852 = 852
Step 2: 852 + 852 = 1704
Step 3: 1704 + 852 = 2556

So, 852*3 = 2556