We have numbers 9543 and 7420. Let's start adding them together.

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

Step 2: We'll start by adding the digits 4 & 2 in column 2 and get 6.

Step 3: We'll start by adding the digits 5 & 4 in column 3 and get 9.

Step 4: We'll start by adding the digits 9 & 7 in column 4 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

So, 9543 + 7420 = 16963.

