We are presented with 3641 and 1331. Let's work out the sum.

Step 1: We'll start by adding the digits 1 & 1 in column 1 and get 2.

Step 2: We'll start by adding the digits 4 & 3 in column 2 and get 7.

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

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

So, 3641 + 1331 = 4972.

