Let's break this down. We're going to add 6964 and 5919 together.

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 6 & 1 in column 2 and get 8.

Step 3: We'll start by adding the digits 9 & 9 in column 3 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 6 & 5 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 6964 + 5919 = 12883.

