1. 1-1 Homework Answers

2. Agenda: 6 th Gr Math: 1-2 HW Page 10 #5-18 all

3. 1-2 Estimating with Whole Numbers Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day

4. Warm Up Find each sum. 1. 3,214 + 5,490 2. 9,225 + 8,652 3. 3,210 + 1,200 4. 8,774 + 2,156 8,704 17,877 4,410 Course 1 1-2 Estimating with Whole Numbers 10,930

5. Problem of the Day Continue the number pattern below. Explain the pattern you found. 3, 6, 10, 15, ___, ___ 21, 28; One possible pattern is to increase the difference between consecutive terms by one more than the difference between preceding consecutive terms. Course 1 1-2 Estimating with Whole Numbers

6. Learn to estimate with whole numbers. Course 1 1-2 Estimating with Whole Numbers

7. Vocabulary compatible number underestimate overestimate Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers

8. Course 1 1-2 Estimating with Whole Numbers Sometimes in math you do not need an exact answer. Instead, you can use an estimate. Estimates are close to the exact answer but are usually easier and faster to find. When estimating, you can round the numbers in the problem to compatible numbers. Compatible numbers are close to the numbers in the problem, and they can help you do math mentally.

9. Course 1 1-2 Estimating with Whole Numbers When rounding, look at the digit to the right of the place to which you are rounding. If that digit is 5 or greater, round up. If that digit is 4 or less, stay put! Remember!

10. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Additional Example 1A: Estimating a Sum or Difference by Rounding Estimate the sum by rounding to the place value indicated. A. 12,345 + 62,167; ten thousands 10,000 Round 12,345 down.Round 62,167 down. + 60,000 __________ The sum is about 70,000. 70,000

11. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Additional Example 1B: Estimating a Sum or Difference by Rounding Estimate the difference by rounding to the place value indicated. B. 4,983 – 2,447; thousands 5,000 Round 4,983 up.Round 2,447 down. – 2,000 __________ The difference is about 3,000. 3,000

12. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Try This: Example 1A Estimate the sum by rounding to the place value indicated. A. 13,235 + 41,139; ten thousands 10,000 Round 13,235 down.Round 41,139 down. + 40,000 __________ The sum is about 50,000. 50,000

13. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Try This: Example 1B Estimate the difference by rounding to the place value indicated. B. 5,723 – 1,393; thousands 6,000 Round 5,723 up.Round 1,393 down. – 1,000 __________ The difference is about 5,000. 5,000

14. Course 1 1-2 Estimating with Whole Numbers An estimate that is less than the exact answer is an underestimate. An estimate that is greater than the exact answer is an overestimate.

15. Course 1 1-2 Estimating with Whole Numbers The area of a rectangle is found by multiplying the length by the width. A = l  w l w Remember!

16. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Additional Example 2: Estimating a Product by Rounding The sixth-grade class wants to paint a wall with white paint. The wall is a rectangle 9 feet tall and 18 feet wide. One quart of paint will cover 100 square feet. How many quarts of paint should the students buy? 9  18 9  20 Overestimate the area of the wall.The actual area is less than 180 square feet. 9  20 = 180 If one quart of paint will cover 100 square feet, then 2 quarts will cover 200 square feet. The students should buy 2 quarts of paint.

17. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Try This: Example 2 The seventh-grade class wants to paint a wall with blue paint. The wall is a rectangle 9 feet tall and 29 feet wide. One quart of paint will cover 100 square feet. How many quarts of paint should the students buy? 9  29 9  30 Overestimate the area of the wall.The actual area is less than 270 square feet. 9  30 = 270 If one quart of paint will cover 100 square feet, then 3 quarts will cover 300 square feet. The students should buy 3 quarts of paint.

18. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Additional Example 3: Estimating a Quotient Using Compatible Numbers Mr. Dehmel will drive 243 miles to the fair at 65 mi/h. About how long will his trip take? 243 ÷ 65 240 ÷ 60 240 and 60 are compatible numbers. Underestimate the speed. Because he underestimated the speed, the actual time will be less than 4 hours.. 240 ÷ 60 = 4 The trip will take about 4 hours.

19. Insert Lesson Title Here Course 1 1-2 Estimating with Whole Numbers Try This: Example 3 Mrs. Blair will drive 103 miles to the airport at 55 mi/h. About how long will her trip take? 103 ÷ 55 100 ÷ 50 100 and 50 are compatible numbers. Underestimate the speed. Because she underestimated the speed, the actual time will be less than 2 hours.. 100 ÷ 50 = 2 The trip will take about 2 hours.

20. Lesson Quiz Estimate each sum or difference by rounding to the place value indicated. 1. 7,420 + 3,527; thousands 2. 47,821 + 19,925; ten thousands 3. 8,254 – 5,703; thousands 4. 66,845 – 24,782; ten thousands 5. One quart of paint covers an area of 100 square feet. How many quarts are needed to paint a wall 8 feet tall and 19 feet wide? 70,000 11,000 Insert Lesson Title Here 2,000 50,000 Course 1 1-2 Estimating with Whole Numbers 2