OK, let's do this. We've got 4211 and 2516 and we're adding them all together.

Step 1: We'll start by adding the digits 1 & 6 in column 1 and get 7.

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

Step 3: We'll start by adding the digits 2 & 5 in column 3 and get 7.

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

So, 4211 + 2516 = 6727.

