Let's solve this addition problem. We have 1084 and 5403, and we need to add them together.

Step 1: We'll start by adding the digits 4 & 3 in column 1 and get 7.

Step 2: We'll start by adding the digits 8 & 0 in column 2 and get 8.

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

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

So, 1084 + 5403 = 6487.

