OK, let's do this. We've got 4105 and 3173 and we're adding them all together.

Step 1: We'll start by adding the digits 5 & 3 in column 1 and get 8.

Step 2: We'll start by adding the digits 0 & 7 in column 2 and get 7.

Step 3: We'll start by adding the digits 1 & 1 in column 3 and get 2.

Step 4: We'll start by adding the digits 4 & 3 in column 4 and get 7.

So, 4105 + 3173 = 7278.

