Okay, we are tasked with adding 5986 and 4986. Let's begin!

Step 1: We'll start by adding the digits 6 & 6 in column 1 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 8 & 8 in column 2 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 9 & 9 in column 3 and get 19.
We'll write down the last digit 9 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 5 & 4 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 5986 + 4986 = 10972.

