Sure thing! We've got 901 and 9942 and we're gonna add them together.

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

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

Step 3: We'll start by adding the digits 9 & 9 in column 3 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 0 & 9 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 901 + 9942 = 10843.

