OK, let's do this. We've got 143 and 6826 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

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

Step 3: We'll start by adding the digits 1 & 8 in column 3 and get 9.

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

So, 143 + 6826 = 6969.

