No problem, let's work through this together. We're starting with 2582 and 7121 and adding them all up.

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

Step 2: We'll start by adding the digits 8 & 2 in column 2 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 5 & 1 in column 3 and get 7.

Step 4: We'll start by adding the digits 2 & 7 in column 4 and get 9.

So, 2582 + 7121 = 9703.

