Okay at the end there will be a decimal
68,070,000,000,000. (well it doesn't have to but anyway)
You want to move the decimal between 6 and 8 because in scientific notation the number has to be between 1 and 10
6.8070000000000 (Now count how many places it takes to get 6.8, I got 13 moves)
So now you want to make the 13 an exponent to 10. (I'm really I'm sorry, I answer this type of question before and I can't really explain it clearly but I know how O_O, anyway...)
it will be 6.807 x 10¹³
I hope this help you out and sorry about me not really explaining it like you wanted to... :(