We've got two numbers: 2120 and 7004. Let's find their sum.

Step 1: We'll start by adding the digits 0 & 4 in column 1 and get 4.

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

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 2 & 7 in column 4 and get 9.

So, 2120 + 7004 = 9124.

