We are presented with 9842 and 4151. Let's work out the sum.

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

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

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 9 & 4 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 9842 + 4151 = 13993.

