OK, let's do this. We've got 6342 and 143 and we're adding them all together.

Step 1: We'll start by adding the digits 2 & 3 in column 1 and get 5.

Step 2: We'll start by adding the digits 4 & 4 in column 2 and get 8.

Step 3: We'll start by adding the digits 3 & 1 in column 3 and get 4.

Step 4: We'll start by adding the digits 6 & 0 in column 4 and get 6.

So, 6342 + 143 = 6485.

