OK, let's do this. We've got 7653 and 9873 and we're adding them all together.

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 & 7 in column 2 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 6 & 8 in column 3 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 7 & 9 in column 4 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

So, 7653 + 9873 = 17526.

