What is 68 billion written as in scientific notation

The answer is:  " 6.8 * 10¹⁰  " .


Note:  68 billion = 68,000,000,000  ; 

           6.8 * 10^(raised to the number of digits that following the
{"single, whole number digit"—which is: "6" }  ;

  ⇒  (which comprises the number "8" PLUS the number of zeros that follow).

So, we have the number: "8" ; which is: 1 digit ;
     and we have: nine "0's" ; which are: 9 digits;


     ⇒  for a total of: "1 digit PLUS 9 digits = 10 digits" .


So;  68 billion = 6.8 * 10^10 ; that is;  

                  ⇒    "  6.8  *  10¹⁰  "  .