OK, let's do this. We've got 1677 and 7621 and we're adding them all together.

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

Step 2: We'll start by adding the digits 7 & 2 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 6 in column 3 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 1 & 7 in column 4 and get 9.

So, 1677 + 7621 = 9298.

