OK, let's do this. We've got 2689 and 172 and we're adding them all together.

Step 1: We'll start by adding the digits 9 & 2 in column 1 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 8 & 7 in column 2 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 8.

Step 4: We'll start by adding the digits 2 & 0 in column 4 and get 2.

So, 2689 + 172 = 2861.

