We've got two numbers: 642 and 17. Let's find their sum.

Step 1: We'll start by adding the digits 2 & 7 in column 1 and get 9.

Step 2: We'll start by adding the digits 4 & 1 in column 2 and get 5.

Step 3: We'll start by adding the digits 6 & 0 in column 3 and get 6.

So, 642 + 17 = 659.

