Not to worry, we've got 5214 and 6665. Let's get to adding them!

Step 1: We'll start by adding the digits 4 & 5 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 2 & 6 in column 3 and get 8.

Step 4: We'll start by adding the digits 5 & 6 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 5214 + 6665 = 11879.

