We have numbers 6420 and 2419. Let's start adding them together.

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 2 & 1 in column 2 and get 3.

Step 3: We'll start by adding the digits 4 & 4 in column 3 and get 8.

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

So, 6420 + 2419 = 8839.

