Not to worry, we've got 2539 and 6419. Let's get to adding them!

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

Step 2: We'll start by adding the digits 3 & 1 in column 2 and get 5.

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

Step 4: We'll start by adding the digits 2 & 6 in column 4 and get 8.

So, 2539 + 6419 = 8958.

