We are presented with 902 and 7782. Let's work out the sum.

Step 1: We'll start by adding the digits 2 & 2 in column 1 and get 4.

Step 2: We'll start by adding the digits 0 & 8 in column 2 and get 8.

Step 3: We'll start by adding the digits 9 & 7 in column 3 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 0 & 7 in column 4 and get 8.

So, 902 + 7782 = 8684.

