Not to worry, we've got 3501 and 6158. Let's get to adding them!

Step 1: We'll start by adding the digits 1 & 8 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 5 & 1 in column 3 and get 6.

Step 4: We'll start by adding the digits 3 & 6 in column 4 and get 9.

So, 3501 + 6158 = 9659.

