OK, let's crack this. We're given 991 and our task is to multiply it by 3. Essentially, we'll be adding 991 to itself 3 times.
Step 1: 0 + 991 = 991
Step 2: 991 + 991 = 1982
Step 3: 1982 + 991 = 2973

So, 991*3 = 2973