Not to worry, we've got 4021 and 2375. Let's get to adding them!

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

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 0 & 3 in column 3 and get 3.

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

So, 4021 + 2375 = 6396.

