We've got two numbers: 140 and 729. Let's find their sum.

Step 1: We'll start by adding the digits 0 & 9 in column 1 and get 9.

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 1 & 7 in column 3 and get 8.

So, 140 + 729 = 869.

