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1-6. Choose the Method of Computation. Course 1. Warm Up. Problem of the Day. Lesson Presentation. 1. __. 10. Warm Up Use mental math to find each fraction of 80. 1. 2. 3. 4. 1. 8. 40. 2. 1. 1. 16. 20. 4. 5. Problem of the Day

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  1. 1-6 Choose the Method of Computation Course 1 Warm Up Problem of the Day Lesson Presentation

  2. 1 __ 10 Warm Up Use mental math to find each fraction of 80. 1.2. 3.4. 1 8 40 2 1 1 16 20 4 5

  3. Problem of the Day About 23% of 600 firefighters are not on duty on any particular day. Steven estimates that about 200 firefighters have the day off. Is his estimate too high or too low? Explain. too high; 25% of 600 is 150

  4. Learn to choose an appropriate method of computation and justify your choice.

  5. Additional Example 1A Evaluate the expression and state the method of computation you used. 4 + 3 + 2 + 10 + 8 + 2 + 5 + 1 There are probably too many numbers to add mentally, but the numbers are small. You can use paper and pencil. 35

  6. Additional Example 1B Evaluate the expression and state the method of computation you used. 4,562 – 397 397 is close to a multiple of 100. You can use mental math. Think: Add 3 to 397 to make 400. Add 3 to 4,562 to compensate. (4,562 + 3) – (397 + 3) 4,565 – 400 4,165

  7. Additional Example 1C Evaluate the expression and state the method of computation you used. 9,288 ÷ 24. The numbers are not compatible, so mental math is not a good idea. You could use paper and pencil, but long division requires several steps. Using a calculator will probably be faster. 387

  8. Check It Out: Example 1A Evaluate the expression and state the method of computation you used. 3 + 7 + 2 + 18 + 7 + 1 + 3 + 1 It might be hard to keep track of all of these numbers if you tried to add mentally. But the numbers themselves are small. You can use paper and pencil. 42

  9. Check It Out: Example 1B Evaluate the expression and state the method of computation you used. 3,442 – 298 298 is close to a multiple of 100. You can use mental math. Think: Add 2 to 298 to make 300. Add 2 to 3,442 to compensate. (3,442 + 2) – (298 + 2) 3,444 – 300 3,144

  10. Check It Out: Example 1C Evaluate the expression and state the method of computation you used. 9,248 ÷ 32. The numbers are not compatible, so mental math is not a good idea. You could use paper and pencil, but long division requires several steps. Using a calculator will probably be faster. 289

  11. Lesson Quiz Evaluate the expression and state the method of computation you used. 1. 17 + 6 + 24 + 35 + 3 + 5 2. 63  197 3. It takes Jupiter approximately 4,344 days to complete one revolution around the Sun. It takes Earth 365 days to revolve around the Sun. How many more days does it take Jupiter to revolve around the Sun than Earth? 90; mental math 12,411; paper and pencil 3,979 days

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