We have numbers 6311 and 6070. Let's start adding them together.

Step 1: We'll start by adding the digits 1 & 0 in column 1 and get 1.

Step 2: We'll start by adding the digits 1 & 7 in column 2 and get 8.

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

Step 4: We'll start by adding the digits 6 & 6 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 6311 + 6070 = 12381.

