Ch2 Rounding and estimating

Ch2 Rounding and estimating
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Ch2 Rounding and estimating

Slide 1 - Diapositive

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Start assignment
Get your Ipad (closed on the corner of your desk), notebook, pen

Make the excersise: 
a) 3.456 - Round to the nearest tenth
b) 23500 - Round to the nearest thousands
c) 245.1695 - Round to the nearest thousandths
d) Write down: What rule can you use when rounding? When do you round up, when do you round down? 

Slide 2 - Diapositive

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Program:
  • Start assignment (5 minutes)
  • Winning team
  • Instruction (10 m)
  • Questions to practice (10 m)
  • Bettermarks (30m)
Today I'll learn... 
...how to round 
...how to estimate the outcome

Slide 3 - Diapositive

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Rounding (4): Everyday situations
  • It is ⁣not⁣ always a good idea to use the rounding rules in real situations. Sometimes this can have a bad result.
  • For example: repaper the walls of your room, 5.2 rolls becomes 6 instead of 5.

Slide 4 - Diapositive

For example: you want to repaper the walls of your room, you calculate you need 5.2 rolls of wallpaper. In this case you havo to round up to 6 rolls of wallpaper, otherwise you wouldn't be able to finish you entire room.
Estimating (1) 
  • Sometimes you do not need an exact solution to a problem, just a rough idea of the result.
  • This is done by making an ⁣estimate. Estimating is usually a much easier calculation and can often be done mentally.
  • To estimate, first ⁣round off⁣ the numbers you are working with. Then calculate with the rounded numbers.
  • For example: 2 295+1 437


Slide 5 - Diapositive

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Estimating with decimal numbers (2)
  • First ⁣round⁣ any decimal numbers to the nearest unit, so they no longer have decimal places.
  • 25.3698+34.73245

  • Estimating is quicker and easier, but less precise.

Slide 6 - Diapositive

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Estimating (3)
  • A ⁣rough estimate⁣ gives an ⁣approximate⁣ solution to a problem that has more than one arithmetic operation. ⁣
  • First ⁣round⁣ any decimal numbers to the nearest unit, so they no longer have decimal places. ⁣
  • For example: 40.456 : 4,78 x 7.97 =

Slide 7 - Diapositive

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Estimate the outcome:
2.34 x 3.58
A
8
B
7
C
7.5

Slide 8 - Quiz

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Estimate the outcome:
34.7834 : 6.982
A
4
B
5
C
6
D
7

Slide 9 - Quiz

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Bettermarks
Make: 6.4, 6.5, 6.6

Done? Check if you finished the whole weekplanner.
You can choose:
- Homework other subject
- Download & Play Cross Math on your ipad 

Slide 10 - Diapositive

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Evaluation
Homework: 
Make: 6.4, 6.5, 6.6



Today I'll learn...
...how to round
...how to estimate the outcome
Exitticket:
Round to the nearest hundredth:
a) 346.794
b) 25.6872
c) 314.9982

Slide 11 - Diapositive

For example: you want to repaper the walls of your room, you calculate you need 5.2 rolls of wallpaper. In this case you havo to round up to 6 rolls of wallpaper, otherwise you wouldn't be able to finish you entire room.

Slide 12 - Diapositive

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