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

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

3. 1-6 Choose the Method of Computation Problem of the Day
Course 1
1-6
Choose the 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. Course 1
1-6
Choose the Method of Computation
Learn to choose an appropriate method of computation and justify your choice.

5. 1-6 Choose the Method of Computation Additional Example 1
Course 1
1-6
Choose the Method of Computation
Additional Example 1
Find the sum:
There are probably too many numbers to add mentally, but the numbers are small. You can use paper and pencil. 35

6. 1-6 Choose the Method of Computation Try This: Example 1
Course 1
1-6
Choose the Method of Computation
Try This: Example 1
Find the sum:
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

7. 1-6 Choose the Method of Computation Additional Example 2
Course 1
1-6
Choose the Method of Computation
Additional Example 2
Find the difference: 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, ) – ( )
4,565 – 400
4,165

8. 1-6 Choose the Method of Computation Try This: Example 2
Course 1
1-6
Choose the Method of Computation
Try This: Example 2
Find the difference: 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, ) – ( )
3,444 – 300
3,144

9. 1-6 Choose the Method of Computation Additional Example 3
Course 1
1-6
Choose the Method of Computation
Additional Example 3
Find the quotient: 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.
9,288 ÷ 24 = 387

10. 1-6 Choose the Method of Computation Try This: Example 3
Course 1
1-6
Choose the Method of Computation
Try This: Example 3
Find the quotient: 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.
9,248 ÷ 32 = 289

11. Insert Lesson Title Here
Course 1
1-6
Choose the Method of Computation
Insert Lesson Title Here
Lesson Quiz
Evaluate the expression and state the method of computation you used.
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