Let's get this math done. We have 6231 and 4905 and we're going to add them all together.

Step 1: We'll start by adding the digits 1 & 5 in column 1 and get 6.

Step 2: We'll start by adding the digits 3 & 0 in column 2 and get 3.

Step 3: We'll start by adding the digits 2 & 9 in column 3 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 6 & 4 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 6231 + 4905 = 11136.

