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# 3.4 rounding decimals

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• ### 3.4 rounding decimals

1. 1. 3.4 Rounding Decimals Friday, October 1, 2010
2. 2. For you notebook (copy this):
3. 3. For you notebook (copy this): Rounding Decimals: to round a decimal to a given place value, look at the digit in the place to the right.
4. 4. For you notebook (copy this): Rounding Decimals: to round a decimal to a given place value, look at the digit in the place to the right. If the digit is 4 or less, round down.
5. 5. For you notebook (copy this): Rounding Decimals: to round a decimal to a given place value, look at the digit in the place to the right. If the digit is 4 or less, round down. If the digit is 5 or greater, round up.
6. 6. Rounding Decimals with a number line
7. 7. Rounding Decimals (write these examples in your notebook.)
8. 8. Rounding Decimals (write these examples in your notebook.) Round the decimal to the place value of the bolded digit.
9. 9. Rounding Decimals (write these examples in your notebook.) Round the decimal to the place value of the bolded digit. 3.23 ------> 3.2, The digit to the right of 2 is 3, so round down.
10. 10. Rounding Decimals (write these examples in your notebook.) Round the decimal to the place value of the bolded digit. 3.23 ------> 3.2, The digit to the right of 2 is 3, so round down. 6.485 ------> 6.49, The digit to the right of 8 is 5, so round up.
11. 11. Rounding Decimals (write these examples in your notebook.) Round the decimal to the place value of the bolded digit. 3.23 ------> 3.2, The digit to the right of 2 is 3, so round down. 6.485 ------> 6.49, The digit to the right of 8 is 5, so round up. 2.83619 -----> 2. 836, The digit to the right of the 6 is 1, so round down.
12. 12. Rounding Decimals (write these examples in your notebook.) Round the decimal to the place value of the bolded digit. 3.23 ------> 3.2, The digit to the right of 2 is 3, so round down. 6.485 ------> 6.49, The digit to the right of 8 is 5, so round up. 2.83619 -----> 2. 836, The digit to the right of the 6 is 1, so round down. 5.961 -----> 6.0, The digit to the right of 9 is 6, so round up. This causes the 5 to become a 6.
13. 13. Now you try: Round to the decimal as speciﬁed: 5.29 (nearest tenth) 7.096 (nearest hundredth) 6.48 (nearest one) 3.9876 (nearest thousandth)
14. 14. Check your answers: Round to the decimal as speciﬁed: 5.29 (nearest tenth) 5.3 7.096 (nearest hundredth) 7.10 6.48 (nearest one) 6 3.9876 (nearest thousandth) 3.988
15. 15. Write this in your notebook: Rounding Small Numbers: You can round a very small number to the place value of its leading digit to help make it easier to understand. In a decimal, the leading digit is the ﬁrst nonzero digit as you read from left to right.
16. 16. Rounding to the Leading Digit (you do not need to copy this)
17. 17. Rounding to the Leading Digit (you do not need to copy this) A guitar was created that is 0.0003937 inch long. Round the length of the guitar to the place value of the leading digit.
18. 18. Rounding to the Leading Digit (you do not need to copy this) A guitar was created that is 0.0003937 inch long. Round the length of the guitar to the place value of the leading digit. To Solve: The ﬁrst nonzero digit as you read 0.0003937 from left to right is 3 and it is in the ten-thousandths place. You should round the digit to the nearest ten thousandth.
19. 19. Rounding to the Leading Digit (you do not need to copy this) A guitar was created that is 0.0003937 inch long. Round the length of the guitar to the place value of the leading digit. To Solve: The ﬁrst nonzero digit as you read 0.0003937 from left to right is 3 and it is in the ten-thousandths place. You should round the digit to the nearest ten thousandth. Because 9 is to the right of the ten-thousandth’s place, round 3 up to 4.
20. 20. Rounding to the Leading Digit (you do not need to copy this) A guitar was created that is 0.0003937 inch long. Round the length of the guitar to the place value of the leading digit. To Solve: The ﬁrst nonzero digit as you read 0.0003937 from left to right is 3 and it is in the ten-thousandths place. You should round the digit to the nearest ten thousandth. Because 9 is to the right of the ten-thousandth’s place, round 3 up to 4. Answer the length rounded to the leading digit is 0.0004 inch.
21. 21. Try these (in your notebook) Round the decimal to the leading digit) 0.058 0.0091 0.0952 0.006192
22. 22. Check your answers. Round the decimal to the leading digit) 0.058 0.06 0.0091 0.009 0.0952 0.10 (you don’t have to have the last 0) 0.006192 0.006
23. 23. When you ﬁnish this slideshow: Take the section quiz (as practice) on classzone.com. Go to assessments, then click on section quizzes. Then click on 3.4 Rounding Decimals. Then play the animated math game on classzone.com. Go to animated math. Then click on Chapter 3: Comparing, Ordering and Rounding Decimals.