We have numbers 1256 and 5723. Let's start adding them together.

Step 1: We'll start by adding the digits 6 & 3 in column 1 and get 9.

Step 2: We'll start by adding the digits 5 & 2 in column 2 and get 7.

Step 3: We'll start by adding the digits 2 & 7 in column 3 and get 9.

Step 4: We'll start by adding the digits 1 & 5 in column 4 and get 6.

So, 1256 + 5723 = 6979.

