際際滷

際際滷Share a Scribd company logo

Tr.Reference 18.ppt

Download as PPT, PDF
U
UgyenTshering51

This document provides instruction on adding and subtracting decimals. It includes examples of adding and subtracting decimals with step-by-step workings. It also has examples applying decimal addition and subtraction to real-world contexts involving distances, temperatures, and quantities measured in millions. Students are guided to estimate their answers to check if they are reasonable. Warm-up, practice, and quiz questions on adding and subtracting decimals are also provided.

1 of 19
Download to read offline
3-2 Adding and Subtracting Decimals Course 2 Warm Up Problem of the Day Lesson Presentation
Warm Up Estimate by rounding to the nearest integer. 1. 3.62 + 4.1 2. 7.47 + (8.23) 3. 8.52 3.16 4. 5.826 + 11.729 8 1 6 Course 2 3-2 Adding and Subtracting Decimals 18
Problem of the Day Complete the magic square. The sum of each row, column, and diagonal must be the same number. 0.5 7 4.625 8.75 6.375 5.25 4 2.25 2.875 Course 2 3-2 Adding and Subtracting Decimals
Learn to add and subtract decimals. Course 2 3-2 Adding and Subtracting Decimals
Course 2 3-2 Adding and Subtracting Decimals One of the coolest summers on record in the Midwest was in 1992. The average summertime temperature that year was 66.8属F. Normally, the average temperature is 4属F higher than it was in 1992. To find the normal average summertime temperature in the Midwest, you can add 66.8属F and 4属F.
Course 2 3-2 Adding and Subtracting Decimals Use zero as a placeholder so that both numbers have the same number of digits after their decimal points. Add each column just as you would add integers. Line up the decimal points. 70.8 66.8 + 4.0 The normal average summertime temperature in the Midwest is 70.8属F.
Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 4.55 + 11.3 Line up the decimal points. Use zero as a placeholder. 4.55 + 11.30 15.85 Add. Estimate 5 + 11 = 16 15.85 is a reasonable answer. Additional Example 1A: Adding Decimals
Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 6.44 + 16 Line up the decimal points. Use zeros as placeholders. 6.44 + 16.00 22.44 Add. Estimate 6 + 16 = 22 22.44 is a reasonable answer. Additional Example 1B: Adding Decimals
Insert Lesson Title Here When adding numbers with the same sign, find the sum of their absolute values. Then use the sign of the numbers. Remember! Course 2 3-2 Adding and Subtracting Decimals
Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is reasonable. 8.33 + (10.972) 8.33 + (10.972) Think: 8.33 + 10.972. Line up the decimal points. Add. 8.33 + (10.972) = 19.302 Use the sign of the two numbers. Additional Example 1C: Adding Decimals 8.330 +10.972 Use zero as a placeholder. 19.302 Estimate 8 + (11) = 19 19.302 is a reasonable answer.
Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 6.78 + 13.2 Line up the decimal points. Use zero as a placeholder. 6.78 + 13.20 19.98 Add. Estimate 7 + 13 = 20 19.98 is a reasonable answer. Check It Out: Example 1A
Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 4.21 + 34 Line up the decimal points. Use zeros as placeholders. 4.21 + 34.00 38.21 Add. Estimate 4 + 34 = 38 38.21 is a reasonable answer. Check It Out: Example 1B
Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is reasonable. 7.89 + (13.852) 7.89 + (13.852) Think: 7.89+ 13.852. Line up the decimal points. Add. 7.89 + (13.852) = 21.742 Use the sign of the two numbers. Check It Out: Example 1C 7.890 +13.852 Use zero as a placeholder. 21.742 Estimate 8 + (14) = 22 21.742 is a reasonable answer.
Course 2 3-2 Adding and Subtracting Decimals Subtract. A. 5.34 2.08 5.34 Line up the decimal points. 2.08 3.26 Subtract. Additional Example 2: Subtracting Decimals B. 28 15.911 28.000 Use zeros as placeholders. 15.911 12.089 Subtract. 7 9 9 10 Line up the decimal points.
Course 2 3-2 Adding and Subtracting Decimals Subtract. A. 3.57 1.46 3.57 Line up the decimal points. 1.46 2.11 Subtract. Check It Out: Example 2 B. 34 12.462 34.000 Use zeros as placeholders. 12.462 21.538 Subtract. 3 9 9 10 Line up the decimal points.
Course 2 3-2 Adding and Subtracting Decimals During one month in the United States, 492.23 million commuter trips were taken on buses, and 26.331 million commuter trips were taken on light rail. What was the total number of trips taken on buses and light rail? Estimate to check whether your answer is reasonable. Line up the decimal points. Use zero as a place holder. 492.230 +26.331 518.561 Add. 492 + 26 = 518 518.561 is a reasonable answer. Estimate The total number of trips was 518.561 million. Additional Example 3: Application
Check It Out: Example 3 Insert Lesson Title Here Course 2 3-2 Adding and Subtracting Decimals Line up the decimal points. Use zero as a place holder. 143.660 +169.831 313.491 Add. 144 + 170 = 314 Estimate The total number of bushels was 313.491 million. In 1999, 143.66 million bushels of corn were grown in the United States. In 2000, the harvest yielded 169.831 million bushels. What was the total production for those two years? Estimate to check whether your answer is reasonable.
Lesson Quiz: Part I Insert Lesson Title Here 2.56; Estimate: 7 4 = 3 Course 2 3-2 Adding and Subtracting Decimals 21.25; Estimate: 7 + 14 = 21 27.66; Estimate: -8 + (-19) = -27 4. 24 3.8 20.2; Estimate: 24 - 4 = 20 Add. Estimate to check whether your answer is reasonable. 1. 6.98 + 14.27 2. 8.46 + (19.2) 3. 6.72 4.16 Subtract. Estimate to check whether your answer is reasonable.
Lesson Quiz: Part II Insert Lesson Title Here Course 2 3-2 Adding and Subtracting Decimals Subtract. Estimate to check whether your answer is reasonable. 5. Renee finished her first lap in the 200 m freestyle event in 28.76 seconds. She completed the second lap in 30.17 seconds. By how much did her time increase in the second lap? Estimate to check whether your answer is reasonable. 1.41 seconds; Estimate: 30 29 = 1

More Related Content

Tr.Reference 18.ppt

  • 1. 3-2 Adding and Subtracting Decimals Course 2 Warm Up Problem of the Day Lesson Presentation
  • 2. Warm Up Estimate by rounding to the nearest integer. 1. 3.62 + 4.1 2. 7.47 + (8.23) 3. 8.52 3.16 4. 5.826 + 11.729 8 1 6 Course 2 3-2 Adding and Subtracting Decimals 18
  • 3. Problem of the Day Complete the magic square. The sum of each row, column, and diagonal must be the same number. 0.5 7 4.625 8.75 6.375 5.25 4 2.25 2.875 Course 2 3-2 Adding and Subtracting Decimals
  • 4. Learn to add and subtract decimals. Course 2 3-2 Adding and Subtracting Decimals
  • 5. Course 2 3-2 Adding and Subtracting Decimals One of the coolest summers on record in the Midwest was in 1992. The average summertime temperature that year was 66.8属F. Normally, the average temperature is 4属F higher than it was in 1992. To find the normal average summertime temperature in the Midwest, you can add 66.8属F and 4属F.
  • 6. Course 2 3-2 Adding and Subtracting Decimals Use zero as a placeholder so that both numbers have the same number of digits after their decimal points. Add each column just as you would add integers. Line up the decimal points. 70.8 66.8 + 4.0 The normal average summertime temperature in the Midwest is 70.8属F.
  • 7. Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 4.55 + 11.3 Line up the decimal points. Use zero as a placeholder. 4.55 + 11.30 15.85 Add. Estimate 5 + 11 = 16 15.85 is a reasonable answer. Additional Example 1A: Adding Decimals
  • 8. Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 6.44 + 16 Line up the decimal points. Use zeros as placeholders. 6.44 + 16.00 22.44 Add. Estimate 6 + 16 = 22 22.44 is a reasonable answer. Additional Example 1B: Adding Decimals
  • 9. Insert Lesson Title Here When adding numbers with the same sign, find the sum of their absolute values. Then use the sign of the numbers. Remember! Course 2 3-2 Adding and Subtracting Decimals
  • 10. Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is reasonable. 8.33 + (10.972) 8.33 + (10.972) Think: 8.33 + 10.972. Line up the decimal points. Add. 8.33 + (10.972) = 19.302 Use the sign of the two numbers. Additional Example 1C: Adding Decimals 8.330 +10.972 Use zero as a placeholder. 19.302 Estimate 8 + (11) = 19 19.302 is a reasonable answer.
  • 11. Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 6.78 + 13.2 Line up the decimal points. Use zero as a placeholder. 6.78 + 13.20 19.98 Add. Estimate 7 + 13 = 20 19.98 is a reasonable answer. Check It Out: Example 1A
  • 12. Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is is reasonable. 4.21 + 34 Line up the decimal points. Use zeros as placeholders. 4.21 + 34.00 38.21 Add. Estimate 4 + 34 = 38 38.21 is a reasonable answer. Check It Out: Example 1B
  • 13. Course 2 3-2 Adding and Subtracting Decimals Add. Estimate to check whether each answer is reasonable. 7.89 + (13.852) 7.89 + (13.852) Think: 7.89+ 13.852. Line up the decimal points. Add. 7.89 + (13.852) = 21.742 Use the sign of the two numbers. Check It Out: Example 1C 7.890 +13.852 Use zero as a placeholder. 21.742 Estimate 8 + (14) = 22 21.742 is a reasonable answer.
  • 14. Course 2 3-2 Adding and Subtracting Decimals Subtract. A. 5.34 2.08 5.34 Line up the decimal points. 2.08 3.26 Subtract. Additional Example 2: Subtracting Decimals B. 28 15.911 28.000 Use zeros as placeholders. 15.911 12.089 Subtract. 7 9 9 10 Line up the decimal points.
  • 15. Course 2 3-2 Adding and Subtracting Decimals Subtract. A. 3.57 1.46 3.57 Line up the decimal points. 1.46 2.11 Subtract. Check It Out: Example 2 B. 34 12.462 34.000 Use zeros as placeholders. 12.462 21.538 Subtract. 3 9 9 10 Line up the decimal points.
  • 16. Course 2 3-2 Adding and Subtracting Decimals During one month in the United States, 492.23 million commuter trips were taken on buses, and 26.331 million commuter trips were taken on light rail. What was the total number of trips taken on buses and light rail? Estimate to check whether your answer is reasonable. Line up the decimal points. Use zero as a place holder. 492.230 +26.331 518.561 Add. 492 + 26 = 518 518.561 is a reasonable answer. Estimate The total number of trips was 518.561 million. Additional Example 3: Application
  • 17. Check It Out: Example 3 Insert Lesson Title Here Course 2 3-2 Adding and Subtracting Decimals Line up the decimal points. Use zero as a place holder. 143.660 +169.831 313.491 Add. 144 + 170 = 314 Estimate The total number of bushels was 313.491 million. In 1999, 143.66 million bushels of corn were grown in the United States. In 2000, the harvest yielded 169.831 million bushels. What was the total production for those two years? Estimate to check whether your answer is reasonable.
  • 18. Lesson Quiz: Part I Insert Lesson Title Here 2.56; Estimate: 7 4 = 3 Course 2 3-2 Adding and Subtracting Decimals 21.25; Estimate: 7 + 14 = 21 27.66; Estimate: -8 + (-19) = -27 4. 24 3.8 20.2; Estimate: 24 - 4 = 20 Add. Estimate to check whether your answer is reasonable. 1. 6.98 + 14.27 2. 8.46 + (19.2) 3. 6.72 4.16 Subtract. Estimate to check whether your answer is reasonable.
  • 19. Lesson Quiz: Part II Insert Lesson Title Here Course 2 3-2 Adding and Subtracting Decimals Subtract. Estimate to check whether your answer is reasonable. 5. Renee finished her first lap in the 200 m freestyle event in 28.76 seconds. She completed the second lap in 30.17 seconds. By how much did her time increase in the second lap? Estimate to check whether your answer is reasonable. 1.41 seconds; Estimate: 30 29 = 1