Okay, we are given 4020 and 2533. Let's add them up step by step.

Step 1: We'll start by adding the digits 0 & 3 in column 1 and get 3.

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

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

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

So, 4020 + 2533 = 6553.

