Okay, we are given 8840 and 6606. Let's add them up step by step.

Step 1: We'll start by adding the digits 0 & 6 in column 1 and get 6.

Step 2: We'll start by adding the digits 4 & 0 in column 2 and get 4.

Step 3: We'll start by adding the digits 8 & 6 in column 3 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 8 & 6 in column 4 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

So, 8840 + 6606 = 15446.

