Okay, we are given 3153 and 6513. Let's add them up step by step.

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

Step 2: We'll start by adding the digits 5 & 1 in column 2 and get 6.

Step 3: We'll start by adding the digits 1 & 5 in column 3 and get 6.

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

So, 3153 + 6513 = 9666.

