We've got two numbers: 6621 and 1342. Let's find their sum.

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 6 & 3 in column 3 and get 9.

Step 4: We'll start by adding the digits 6 & 1 in column 4 and get 7.

So, 6621 + 1342 = 7963.

