1. EXAMPLE 1 Biking The map shows biking times for a trail. Estimating Sums and Differences

2. EXAMPLE 1 Biking The map shows biking times for a trail. a.Estimate how long it takes to bike from the trailhead to the swinging bridge and then to the waterfall. Estimating Sums and Differences

3. EXAMPLE 1 Biking The map shows biking times for a trail. a.Estimate how long it takes to bike from the trailhead to the swinging bridge and then to the waterfall. b.The biking time from the swinging bridge, past the waterfall, to the trailhead is 208 minutes. Estimate the number of minutes it takes to bike from the waterfall to the trailhead. Estimating Sums and Differences

4. EXAMPLE 1 SOLUTION a.Round the two times to the same place value. Then add. Estimating Sums and Differences

5. EXAMPLE 1 SOLUTION a.Round the two times to the same place value. Then add. Estimating Sums and Differences

6. EXAMPLE 1 SOLUTION a.Round the two times to the same place value. Then add. Round each number to the nearest ten. Estimating Sums and Differences

7. EXAMPLE 1 SOLUTION a.Round the two times to the same place value. Then add. Round each number to the nearest ten. Round 28 up to 30. Round 114 down to 110. Estimating Sums and Differences

8. EXAMPLE 1 SOLUTION a.Round the two times to the same place value. Then add. Round each number to the nearest ten. Estimating Sums and Differences Round 28 up to 30. Round 114 down to 110.

9. EXAMPLE 1 SOLUTION a.Round the two times to the same place value. Then add. Round each number to the nearest ten. ANSWER: It takes about 140 minutes to bike from the trailhead to the swinging bridge and then to the waterfall. Estimating Sums and Differences Round 28 up to 30. Round 114 down to 110.

10. EXAMPLE 1 b. Estimating Sums and Differences

11. EXAMPLE 1 Round each number to the nearest hundred. b. Estimating Sums and Differences

12. EXAMPLE 1 Round each number to the nearest hundred. Round 208 down to 200. Round 114 down to 100. b. Estimating Sums and Differences

13. EXAMPLE 1 Round each number to the nearest hundred. b. Estimating Sums and Differences Round 208 down to 200. Round 114 down to 100.

14. EXAMPLE 1 Round each number to the nearest hundred. ANSWER: It takes about 100 minutes to bike from the waterfall to the trailhead. b. Estimating Sums and Differences Round 208 down to 200. Round 114 down to 100.

15. GUIDED PRACTICE for Example 1 Estimate the sum or difference.

16. GUIDED PRACTICE Estimate the sum or difference. ANSWER 90 for Example 1

17. GUIDED PRACTICE Estimate the sum or difference. for Example 1

18. GUIDED PRACTICE Estimate the sum or difference. for Example 1 ANSWER 1100

19. GUIDED PRACTICE Estimate the sum or difference. for Example 1

20. GUIDED PRACTICE Estimate the sum or difference. ANSWER 40 for Example 1

21. GUIDED PRACTICE Estimate the sum or difference. for Example 1

22. GUIDED PRACTICE Estimate the sum or difference. ANSWER 530 for Example 1