OK, let's do this. We've got 2823 and 3512 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 2 in column 1 and get 5.

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

Step 3: We'll start by adding the digits 8 & 5 in column 3 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 2 & 3 in column 4 and get 6.

So, 2823 + 3512 = 6335.

