Let's solve this addition problem. We have 7042 and 6864, and we need to add them together.

Step 1: We'll start by adding the digits 2 & 4 in column 1 and get 6.

Step 2: We'll start by adding the digits 4 & 6 in column 2 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 0 & 8 in column 3 and get 9.

Step 4: We'll start by adding the digits 7 & 6 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 7042 + 6864 = 13906.

