In astronomy, distance measurements are very large.  There is a way to express these very large distances in the universe, galaxy, or solar system.  Scientific notation allows large numbers to be expressed simply.
    Scientific notation is based on powers of ten.  Before we go any further, let's review some things about powers of ten.

        The number ten (10) is ten to the first power (10¹).
        The number one hundred (100) is ten to the second power (10²).
        The number one thousand (1000) is ten to the thirdpower (10³).
        The number ten thousand (10,000) is ten to the first power (10⁴).

    There is a pattern here.  Numbers that consist of one (1) followed by several zeros (0) can be written as powers of ten.  The power of ten is just the number of zeros in the number.

    A power of ten can also be thought of as the number of times ten must be multiplied by itself to get the original number.  Look for the pattern in the numbers below.

    Write the following numbers as powers of ten
        1.  100 ________            2.  10,000 ________        3.  1,000 ___________
 
        4. 1,000,000 ___________    5.  100,000 __________  6.  10,000,000 _____________

A large number can be put into scientific notation by writing it as the first digit of a number, followed by a decimal point, followed by all of the other digits in the number, multiplied by a power of ten.  The number below is in scientific notation.
                                8.75 X 10⁸
    To convert a large number to scientific notation, you must do two things:
        1.  Move the decimal point in the number to the left so that it is between the left-end digit in the number and the digit that is next to theleft end.  If the number does not have a deciaml point to start with, put on the extreme right-hand end of the number before beginning.

        2.  Multiply the number by a power of ten.  The power should be equal to the numbe of digits that you had to pass when you moved the decimal point to the left in step 1

            Let's see how we can convert the number 8415.7 to scientific notation.  First wirte the number.
                    8415.7

            Next, move the decimal point between the 8 and the 4
                    8.4157

            Next, notice that you had to move the decimal point three digits to the left.  Multiply by ten to the third power.
                    8.4157 X 10³
 

      Write the following numbers in scientific notation
            1.  500 __________       2.  4,572 ______________    3.  5,321_________________

            4. 725,000 __________________  5. 95,476.5 __________________________

            6.  5,895,000 ________________  7.  345.67 ___________________

            8.  25,150,000,000 _______________        9.  675,123.25 ________________________