Let's say we had the massive number
6,230,000,000
which we can shorten it to saying "6.23 billion" and that allows us to drop all the extra zeros at the end.
When writing it in scientific notation, we would say [tex]6.23 \times 10^9[/tex] and the [tex]\times 10^9[/tex] portion indicates "times ten to the ninth power". This is the place holder for "billion". It means we'll move the decimal point 9 spots to the right to go from 6.23 back to the original massive number shown above.
In short, scientific notation allows us to represent really large numbers in a compact way. It's useful to be able to communicate to a friend about whatever number you're referring to. One application is trying to find vast distances in outer space which tend to be very larger numbers. There are many other applications for scientific notation.
