We've got two numbers: 1390 and 8090. Let's find their sum.

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

Step 2: We'll start by adding the digits 9 & 9 in column 2 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 3 & 0 in column 3 and get 4.

Step 4: We'll start by adding the digits 1 & 8 in column 4 and get 9.

So, 1390 + 8090 = 9480.

