Let's break this down. We're going to add 4587 and 8911 together.

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

Step 2: We'll start by adding the digits 8 & 1 in column 2 and get 9.

Step 3: We'll start by adding the digits 5 & 9 in column 3 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 4 & 8 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 4587 + 8911 = 13498.

