Here we go! We're going to add 2004 and 6445 together.

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 0 & 4 in column 2 and get 4.

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 2 & 6 in column 4 and get 8.

So, 2004 + 6445 = 8449.

