We have numbers 9102 and 8539. Let's start adding them together.

Step 1: We'll start by adding the digits 2 & 9 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 0 & 3 in column 2 and get 4.

Step 3: We'll start by adding the digits 1 & 5 in column 3 and get 6.

Step 4: We'll start by adding the digits 9 & 8 in column 4 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

So, 9102 + 8539 = 17641.

