Let's get this math done. We have 7892 and 7971 and we're going to add them all together.

Step 1: We'll start by adding the digits 2 & 1 in column 1 and get 3.

Step 2: We'll start by adding the digits 9 & 7 in column 2 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 8 & 9 in column 3 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 7 & 7 in column 4 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

So, 7892 + 7971 = 15863.

