We have numbers 2859 and 2129. Let's start adding them together.

Step 1: We'll start by adding the digits 9 & 9 in column 1 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 5 & 2 in column 2 and get 8.

Step 3: We'll start by adding the digits 8 & 1 in column 3 and get 9.

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

So, 2859 + 2129 = 4988.

