Question

Which of these are written in scientific notation

Answer 1

A properly written number in scientific notation has the form:
+/- A*10^n
where +/- is either plus or minus
A is a decimal number (or integer) where 1<= A < 10
and n is a positive or negative integer.

According to these rules, 
120,000,000 is written in scientific notation as
1.2 * 10^8
so we need to move the decimal point 8 places to the left and multiply by 10^8.