- (2 min) Reminders

- Homework must be turned in on time.
- Every week bring your calculator and pencil.

- (10 min) Exponents

An*exponent*tells how many times a number is to be multiplied by itself. What is 2 x 2 x 2 x 2 ? [16] It can also be written as 2^{4}. 4 is the exponent or the power of 2. We say that 2 is raised to the 4th power.

DO NOT CONFUSE 2^{4}WITH 2 x 4. THEY ARE NOT THE SAME.

2 x 4 = 8 and 2^{4}=16.

What is 4 x 4 x 4? [64] How would you write it with an exponent? [4^{3}]

What is 3^{2}? [9] What is 5^{3}? [125]

There is a story about exponents:Once upon a time there was a rich king who had a mathematical wise man. the wise man told the king that he would work for a small price. He brought a checkerboard to the king and said: On the first square put one grain of rice. On the second square, double that. On every square, double the number of grains of rice that were oon the previous square. The king agreed, but he lost his entire kingdom to the wise man. The king owed the wise man 18 quntillion grains of rice. This is more rice than has ever been grown in the history of the world!!!

- (10 min) Powers of 10

We write 10 X 10 X 10 = 1000 as 10^{3}. Powers of 10 are very easy to work with because all you do is count the zeroes.4 x 10

Scientists must work with very large numbers. For example the distance from the sun to the planet Neptune is about 2,790,000,000 miles. We can express this as:^{5}= 4 x 100000 = 400000 6 x 10^{8}= 6 x 100000000 = 600000000

2.79 x 1000000000 or ...

2.79 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 or...

2.79 x 10^{9}These numbers are easier to write and compute when expressed as scientific notation. In scientific notation, the number is expressed as a number between 1 and 10 and then multiplied by a power of 10. The number of the exponent is the number of zeros added on the end. If there is a decimal point, you have to move the decimal point to the right, counting for each, and then add zero's on the end to finish off.

1.997 x 10

We will not discuss negative (-) exponents for very small numbers.^{3}= 1997 1492 = 1.492 x 10^{3}

- (Remainder of class) In-class exercise

- Hand out homework to students as they successfully complete the in-class exercise