Not to worry, we've got 5445 and 8042. Let's get to adding them!

Step 1: We'll start by adding the digits 5 & 2 in column 1 and get 7.

Step 2: We'll start by adding the digits 4 & 4 in column 2 and get 8.

Step 3: We'll start by adding the digits 4 & 0 in column 3 and get 4.

Step 4: We'll start by adding the digits 5 & 8 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 5445 + 8042 = 13487.

