Ch2 Rounding and estimating

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 1

Ch2 Rounding and estimating

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? 

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

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.

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

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.

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 =

Estimate the outcome:
2.34 x 3.58

1. 8
2. 7
3. 7.5

Estimate the outcome:
34.7834 : 6.982

1. 4
2. 5
3. 6
4. 7

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 

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

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.