Let's solve this addition problem. We have 3156 and 6440, and we need to add them together.

Step 1: We'll start by adding the digits 6 & 0 in column 1 and get 6.

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

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

Step 4: We'll start by adding the digits 3 & 6 in column 4 and get 9.

So, 3156 + 6440 = 9596.

