Okay, we are given 198709110 and 800070825. Let's add them up step by step.

Step 1: We'll start by adding the digits 0 & 5 in column 1 and get 5.

Step 2: We'll start by adding the digits 1 & 2 in column 2 and get 3.

Step 3: We'll start by adding the digits 1 & 8 in column 3 and get 9.

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

Step 5: We'll start by adding the digits 0 & 7 in column 5 and get 7.

Step 6: We'll start by adding the digits 7 & 0 in column 6 and get 7.

Step 7: We'll start by adding the digits 8 & 0 in column 7 and get 8.

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

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

So, 198709110 + 800070825 = 998779935.

