Okay, we are given 3346 and 1007. Let's add them up step by step.

Step 1: We'll start by adding the digits 6 & 7 in column 1 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

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

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

Step 4: We'll start by adding the digits 3 & 1 in column 4 and get 4.

So, 3346 + 1007 = 4353.

