Alright, let's solve this problem step by step. We have 7746646240 and 4372351751 and we're adding them together.

Step 1: We'll start by adding the digits 0 & 1 in column 1 and get 1.

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

Step 3: We'll start by adding the digits 2 & 7 in column 3 and get 9.

Step 4: We'll start by adding the digits 6 & 1 in column 4 and get 7.

Step 5: We'll start by adding the digits 4 & 5 in column 5 and get 9.

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

Step 7: We'll start by adding the digits 6 & 2 in column 7 and get 8.

Step 8: We'll start by adding the digits 4 & 7 in column 8 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 9: We'll start by adding the digits 7 & 3 in column 9 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 10: We'll start by adding the digits 7 & 4 in column 10 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 7746646240 + 4372351751 = 12118997991.

