Unit 5 Exponential Notation

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Expressing Numbers in Exponential Notation

When numbers are really large or really small, it is sometimes convenient to express them in exponential notation. A good rule of thumb is to express numbers that fall between 10,000 and 0.0001 in regular notation. Numbers that fall on either side of this range are best expressed in exponential notation.

Converting Numbers from Regular to Exponential Notation

For numbers Larger than 1, the exponent is positive. For numbers less than 1, the exponent is negative. The magnitude of the exponent is determined by how many spaces the decimal is moved.

ie) 2,156 --> 2.156 x 103

0.00874 --> 8.74 x 10-3

Converting Numbers from Exponential Notation to Regular Notation

The object is to make the exponent following the 10, go to zero. Starting with a positive exponent means moving the decimal to the right until the exponent reaches zero.

2.34 x 104 --> 23,400

Starting with a negative exponent means moving the decimal to the left until the exponent reaches zero.

4.56 x 10-2 --> 0.0456

Operations With Exponential Notation

Entering numbers in exponential notation into your calculator.

Look for the EE or EXP button on your calculator. To enter 2.34 x 105 into your calculator you enter the number 2.34, then press EXP or EE, then enter 5, the number you want for the exponent. To enter a number that has a negative exponent, such as 7.65 x 10-3 into your calculator, enter the number 7.65, then press EXP or EE, then press the change the sign button (+/-), then enter 3, the number you want in the exponent.

Multiplication and division with a calculator

Be sure to enter the numbers into your calculator as explained above.

Addition and subtraction with a calculator

Unlike performing addition and subtraction without a calculator, numbers with different exponents can be entered into your calculator. Be sure to enter the numbers into your calculator as explained above.

 

Check out this applet on powers of ten!

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html

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