We've got two numbers: 5358 and 2399. Let's find their sum.

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

Step 2: We'll start by adding the digits 5 & 9 in column 2 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 3 & 3 in column 3 and get 7.

Step 4: We'll start by adding the digits 5 & 2 in column 4 and get 7.

So, 5358 + 2399 = 7757.

