Let's get this math done. We have 2121 and 7642 and we're going to add them all together.

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

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

Step 3: We'll start by adding the digits 1 & 6 in column 3 and get 7.

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

So, 2121 + 7642 = 9763.

