Not to worry, we've got 5575 and 4424. Let's get to adding them!

Step 1: We'll start by adding the digits 5 & 4 in column 1 and get 9.

Step 2: We'll start by adding the digits 7 & 2 in column 2 and get 9.

Step 3: We'll start by adding the digits 5 & 4 in column 3 and get 9.

Step 4: We'll start by adding the digits 5 & 4 in column 4 and get 9.

So, 5575 + 4424 = 9999.

