OK, let's do this. We've got 3971 and 4910 and we're adding them all together.

Step 1: We'll start by adding the digits 1 & 0 in column 1 and get 1.

Step 2: We'll start by adding the digits 7 & 1 in column 2 and get 8.

Step 3: We'll start by adding the digits 9 & 9 in column 3 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 3 & 4 in column 4 and get 8.

So, 3971 + 4910 = 8881.

