We've got two numbers: 9604 and 4989. Let's find their sum.

Step 1: We'll start by adding the digits 4 & 9 in column 1 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 8 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 9 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 9 & 4 in column 4 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

So, 9604 + 4989 = 14593.

