OK, let's do this. We've got 31390714 and 28268428 and we're adding them all together.

Step 1: We'll start by adding the digits 4 & 8 in column 1 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 1 & 2 in column 2 and get 4.

Step 3: We'll start by adding the digits 7 & 4 in column 3 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 0 & 8 in column 4 and get 9.

Step 5: We'll start by adding the digits 9 & 6 in column 5 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 6: We'll start by adding the digits 3 & 2 in column 6 and get 6.

Step 7: We'll start by adding the digits 1 & 8 in column 7 and get 9.

Step 8: We'll start by adding the digits 3 & 2 in column 8 and get 5.

So, 31390714 + 28268428 = 59659142.

