Here we go! We're going to add 4001 and 5578 together.

Step 1: We'll start by adding the digits 1 & 8 in column 1 and get 9.

Step 2: We'll start by adding the digits 0 & 7 in column 2 and get 7.

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

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

So, 4001 + 5578 = 9579.

