No problem, let's work through this together. We're starting with 9401 and 2558 and adding them all up.

Step 1: We'll start by adding the digits 1 & 8 in column 1 and get 9.

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

Step 3: We'll start by adding the digits 4 & 5 in column 3 and get 9.

Step 4: We'll start by adding the digits 9 & 2 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 9401 + 2558 = 11959.

