Okay, we are tasked with adding 5444 and 2455. Let's begin!

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

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

Step 3: We'll start by adding the digits 4 & 4 in column 3 and get 8.

Step 4: We'll start by adding the digits 5 & 2 in column 4 and get 7.

So, 5444 + 2455 = 7899.

