1. 1-5 Choosing a Method of Computation Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes

2. 1-5 Choosing a Method of Computation Warm Up Use mental math to find each fraction of 80. 1. 2. 3. 4. 40 8 20 1 10 __ 1 2 16 1 4 1 5

3. 1-5 Choosing a Method of Computation 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. 1-5 Choosing a Method of Computation Learn to choose an appropriate method of computation and justify your choice.

5. 1-5 Choosing a Method of Computation Additional Example 1A Simplify the expression and state the method of computation you used. Look for sums that are multiples of 10. You can use mental math. 35 4 + 3 + 2 + 10 + 8 + 2 + 5 + 1

6. 1-5 Choosing a Method of Computation Additional Example 1B Simplify the expression and state the method of computation you used. 4,562 – 397 397 is close to a multiple of 100. You can use pencil and paper. (4,562 + 3) – (397 + 3) 4,565 – 400 4,165 Think: Add 3 to 397 to make 400. Add 3 to 4,562 to compensate.

7. 1-5 Choosing a Method of Computation Additional Example 1C Simplify 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. 1-5 Choosing a Method of Computation Look for sums that are multiples of 10. You can use mental math. 42 Check It Out: Example 1A Simplify the expression and state the method of computation you used. 3 + 7 + 2 + 18 + 7 + 1 + 3 + 1

9. 1-5 Choosing a Method of Computation Check It Out: Example 1B Simplify 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. (3,442 + 2) – (298 + 2) 3,444 – 300 3,144 Think: Add 2 to 298 to make 300. Add 2 to 3,442 to compensate.

10. 1-5 Choosing a Method of Computation Check It Out: Example 1C Simplify 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. 1-5 Choosing a Method of Computation Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems

12. 1-5 Choosing a Method of Computation Lesson Quiz Simplify 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? 12,411; paper and pencil 90; mental math 3,979 days; calculator

13. 1-5 Choosing a Method of Computation 1. Evaluate the expression and state method of computation you used. 16 + 3 + 21 + 37 + 4 + 9 A. 90; mental math B. 100; paper and pencil C. 80; mental math D. 80; paper and pencil Lesson Quiz for Student Response Systems

14. 1-5 Choosing a Method of Computation 2. Evaluate the expression and state method of computation you used. 74  189 A. 14,000; mental math B. 13,986; paper and pencil C. 14,364; mental math D. 14,364; paper and pencil Lesson Quiz for Student Response Systems

15. 1-5 Choosing a Method of Computation 3. Kenneth’s company produces 346 cycles per day. How many cycles does it produce in 43 days? A. 13,470 cycles; mental math B. 13,470 cycles; paper and pencil C. 14,000 cycles; mental math D. 14,878 cycles; calculator Lesson Quiz for Student Response Systems