In 2008, there were 6.7 * 10^9 people living on earth. what is that number in standard
notation?

6,700,000,000

Step-by-step explanation:

Standard Notation is the normal way of writing numbers.

Scientific notation of 6.7 * 10^9  would mean we need to move the decimal point "9" units "to the right" and arrive at our normal standard form of the number.

So, we move 1 decimal place and create 67. Then with the next 8 moves (to the right), we add 8 more zeros, so the number actually becomes:

6,700,000,000

This is 6 billion, 700 million.

This is the normal standard way (standard notation) of writing numbers.