OK, let's do this. We've got 5949 and 4026 and we're adding them all together.

Step 1: We'll start by adding the digits 9 & 6 in column 1 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 4 & 2 in column 2 and get 7.

Step 3: We'll start by adding the digits 9 & 0 in column 3 and get 9.

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

So, 5949 + 4026 = 9975.

