Okay, we are given 2321 and 4073. Let's add them up step by step.

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

Step 2: We'll start by adding the digits 2 & 7 in column 2 and get 9.

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

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

So, 2321 + 4073 = 6394.

