Scientific Notation. Section 7-1 Part 2

Transcription

1 Scientific Notation Section 7-1 Part 2

2 Goals Goal To write numbers in scientific notation and standard form. To compare and order numbers using scientific notation.

3 Vocabulary Scientific Notation

4 Powers of 10 The table shows relationships between several powers of 10. Each time you divide by 10, the exponent in the power decreases by 1 and the decimal point in the value moves one place to the left. Each time you multiply by 10, the exponent in the power increases by 1 and the decimal point in the value moves one place to the right.

5 Powers of 10 You can find the product of a number and a power of 10 by moving the decimal point of the number. If the exponent is positive, move the decimal point to the right. If the exponent is negative, move the decimal point to the left. You may need to write zeros to the right or left of the number in order to move the decimal point.

6 Multiply. Example: Multiplying by Powers of 10 A. 14 x Since the exponent is a positive 4, move the decimal point 4 places to the right. 140,000 B. 3.6 x Since the exponent is a negative 5, move the decimal point 5 places to the left

7 Your Turn: Multiply. A. 2.5 x Since the exponent is a positive 5, move the decimal point 5 places to the right. 250,000 B x Since the exponent is a negative 3, move the decimal point 3 places to the left

8 Definition Scientific Notation - is a way to express numbers that are very large or very small. Powers of 10 are used when writing numbers in scientific notation. Numbers written in scientific notation are expressed as 2 factors. One factor is a number greater than or equal to 1. The other factor is a power of 10. Example:

9 Scientific Notation The first part is a number that is greater than or equal to 1 and less than 10. The second part is a power of 10.

10 Why Use Scientific Notation? For very large and very small numbers, these numbers can be converted into scientific notation to express them in a more concise form. Numbers expressed in scientific notation can be used in a computation with far greater ease.

11 Example: Recognizing Scientific Notation Is the number written in scientific notation? Explain No, 53 is not less than Yes No, 0.35 is not greater than or equal to 1 No, 100 is not in power of 10 form

12 Your Turn: Is the number written in scientific notation? Explain Yes No, 12.9 is greater than Yes No, is not greater than or equal to 1

13 Procedure: Writing Numbers in Scientific Notation 1. Place the decimal point so that there is one nonzero digit to the left of the decimal point. 2. Count the number of decimal places the decimal point has moved from the original number. This will be the exponent on the If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.

14 Example: Writing Numbers in Scientific Notation Write the number in scientific notation. A Think: The decimal needs to move 3 places to get a number between 1 and x 10-3 Think: The number is less than 1, so the exponent will be negative. So written in scientific notation is 7.09 x 10 3.

15 Example: Writing Numbers in Scientific Notation Write the number in scientific notation. B. 23,000,000,000 Think: The decimal needs to move 10 places to get a number between 1 and x Think: The number is greater than 1, so the exponent will be positive. So 23,000,000,000 written in scientific notation is 2.3 x

16 Your Turn: Write the number in scientific notation. A Think: The decimal needs to move 4 places to get a number between 1 and x 10-4 Think: The number is less than 1, so the exponent will be negative. So written in scientific notation is 8.11 x 10 4.

17 Your Turn: Write the number in scientific notation. B. 480,000,000 Think: The decimal needs to move 8 places to get a number between 1 and x 10 8 Think: The number is greater than 1, so the exponent will be positive. So 480,000,000 written in scientific notation is 4.8 x 10 8.

18 Reading Math Standard form refers to the usual way that numbers are written not in scientific notation.

19 Procedure: Writing Numbers in Standard Form 1. Simply move the decimal point to the right for positive exponent Move the decimal point to the left for negative exponent 10. (Use zeros to fill in places.)

20 Example: Writing a Number in Standard Form Write the number in standard form. A x x Think: Move the decimal right 5 places. 135,000

21 Example: Writing a Number in Standard Form Write the number in standard form. B. 2.7 x x Think: Move the decimal left 3 places

22 A x x 10 9 Your Turn: Write the number in standard form Think: Move the decimal right 9 places. 2,870,000,000

23 Your Turn: Write the number in standard form. B. 1.9 x x Think: Move the decimal left 5 places

24 Example: Comparing Numbers in Scientific Notation A certain cell has a diameter of approximately 4.11 x 10-5 meters. A second cell has a diameter of 1.5 x 10-5 meters. Which cell has a greater diameter? 4.11 x x > 1.5 Compare the exponents. Compare the values between 1 and 10. Notice that 4.11 x 10-5 > 1.5 x The first cell has a greater diameter.

25 Your Turn: A star has a diameter of approximately 5.11 x 10 3 kilometers. A second star has a diameter of 5 x 10 4 kilometers. Which star has a greater diameter? 5.11 x x 10 4 Compare the exponents. Notice that 3 < 4. So 5.11 x 10 3 < 5 x 10 4 The second star has a greater diameter.

26 Example: Ordering Numbers in Scientific Notation Order the list of numbers from least to greatest. Step 1 List the numbers in order by powers of 10. Step 2 Order the numbers that have the same power of 10

27 Your Turn: Order the list of numbers from least to greatest. Step 1 List the numbers in order by powers of x 10-12, 4 x 10-3, 5.2 x 10-3, 3 x 10 14, 4.5 x 10 14, 4.5 x Step 2 Order the numbers that have the same power of 10

28 Joke Time Did you hear about the red ship and the blue ship that collided? Both crews were marooned! What did one shark say to the other while eating a clownfish? This tastes funny! What did the cobbler say when a cat wandered into his shop? Shoe!