We've got two numbers: 8460 and 8519. Let's find their sum.

Step 1: We'll start by adding the digits 0 & 9 in column 1 and get 9.

Step 2: We'll start by adding the digits 6 & 1 in column 2 and get 7.

Step 3: We'll start by adding the digits 4 & 5 in column 3 and get 9.

Step 4: We'll start by adding the digits 8 & 8 in column 4 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

So, 8460 + 8519 = 16979.

