Let's solve this addition problem. We have 3003 and 5646, and we need to add them together.

Step 1: We'll start by adding the digits 3 & 6 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 & 6 in column 3 and get 6.

Step 4: We'll start by adding the digits 3 & 5 in column 4 and get 8.

So, 3003 + 5646 = 8649.

