OK, let's do this. We've got 1003 and 2049 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 9 in column 1 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 4 in column 2 and get 5.

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

Step 4: We'll start by adding the digits 1 & 2 in column 4 and get 3.

So, 1003 + 2049 = 3052.

