We have numbers 4005 and 5446. Let's start adding them together.

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

Step 2: We'll start by adding the digits 0 & 4 in column 2 and get 5.

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

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

So, 4005 + 5446 = 9451.

