OK, let's do this. We've got 4004 and 2181 and we're adding them all together.

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

Step 2: We'll start by adding the digits 0 & 8 in column 2 and get 8.

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

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

So, 4004 + 2181 = 6185.

