Okay, we are given 3643 and 6122. Let's add them up step by step.

Step 1: We'll start by adding the digits 3 & 2 in column 1 and get 5.

Step 2: We'll start by adding the digits 4 & 2 in column 2 and get 6.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 7.

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

So, 3643 + 6122 = 9765.

