Let's solve this addition problem. We have 5403 and 1165, and we need to add them together.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

Step 2: We'll start by adding the digits 0 & 6 in column 2 and get 6.

Step 3: We'll start by adding the digits 4 & 1 in column 3 and get 5.

Step 4: We'll start by adding the digits 5 & 1 in column 4 and get 6.

So, 5403 + 1165 = 6568.

