1-4 Choosing a Method of Computation

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Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

Lesson QuizzesLesson Quizzes

1-4 Choosing a Method of Computation

Warm UpUse mental math to find each fraction of 80.

1. 2.

3. 4.

40 8

20

110 __1

2

1614

15

1-4 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

1-4 Choosing a Method of Computation

Prep for MA.6.A.1.1 Explain and justify procedures for multiplying and dividing fractions and decimals.

Also Review of MA.5.A.1.2

Sunshine State Standards

1-4 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

1-4 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.

1-4 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

1-4 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

1-4 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.

1-4 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

1-4 Choosing a Method of Computation

Standard Lesson Quiz

Lesson Quizzes

Lesson Quiz for Student Response Systems

1-4 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

1-4 Choosing a Method of Computation

1. Simplify the expression and state the 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

1-4 Choosing a Method of Computation

2. Simplify the expression and state the 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

1-4 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