OK, let's do this. We've got 673 and 2106 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 7 & 0 in column 2 and get 7.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 7.

Step 4: We'll start by adding the digits 0 & 2 in column 4 and get 2.

So, 673 + 2106 = 2779.

