OK, let's do this. We've got 3003 and 6926 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 0 & 9 in column 3 and get 9.

Step 4: We'll start by adding the digits 3 & 6 in column 4 and get 9.

So, 3003 + 6926 = 9929.

