Scientific notation is used to express very large or very small numbers. A number in scientific notation is written as the product of a number (integer or decimal) and a power of 10. This number is always 1 or more and less than 10.

For example, there are approximately 6,000,000,000 humans on earth. This number could be written in scientific notation as 6x10⁹. The number 6,000,000,000 is equivalent to 6*1,000,000,000. The number 1,000,000,000 is equivalent to 10⁹ or 10*10*10*10*10*10*10*10*10.

A number can be converted to scientific notation by increasing the power of ten by one for each place the decimal point is moved to the left. In the example above, the decimal point was moved 9 places to the left to form a number more than 1 and less than 10.

Scientific notation numbers may be written in different forms. The number 6x10⁹ could also be written as 6e+9. The +9 indicates that the decimal point would be moved 9 places to the right to write the number in standard form.