OK, let's do this. We've got 7701 and 3091 and we're adding them all together.

Step 1: We'll start by adding the digits 1 & 1 in column 1 and get 2.

Step 2: We'll start by adding the digits 0 & 9 in column 2 and get 9.

Step 3: We'll start by adding the digits 7 & 0 in column 3 and get 7.

Step 4: We'll start by adding the digits 7 & 3 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 7701 + 3091 = 10792.

