Alright, let's solve this problem step by step. We have 7852 and 6406 and we're adding them together.

Step 1: We'll start by adding the digits 2 & 6 in column 1 and get 8.

Step 2: We'll start by adding the digits 5 & 0 in column 2 and get 5.

Step 3: We'll start by adding the digits 8 & 4 in column 3 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 7 & 6 in column 4 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

So, 7852 + 6406 = 14258.

