Okay, we are tasked with adding 6123 and 2563. Let's begin!

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

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

Step 3: We'll start by adding the digits 1 & 5 in column 3 and get 6.

Step 4: We'll start by adding the digits 6 & 2 in column 4 and get 8.

So, 6123 + 2563 = 8686.

