Let's get this math done. We have 4205 and 5394 and we're going to add them all together.

Step 1: We'll start by adding the digits 5 & 4 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 2 & 3 in column 3 and get 5.

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

So, 4205 + 5394 = 9599.

