We've got two numbers: 5242 and 2123. Let's find their sum.

Step 1: We'll start by adding the digits 2 & 3 in column 1 and get 5.

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

Step 3: We'll start by adding the digits 2 & 1 in column 3 and get 3.

Step 4: We'll start by adding the digits 5 & 2 in column 4 and get 7.

So, 5242 + 2123 = 7365.

