Tuesday, October 27, 2009

Why We Estimate

Why we estimate: The reasons why we estimate are

To get closer to an answer

To make a problem easier

And to know what to expect from a calculation

You have 1.36L of OJ and theres 4 people that you need to share it to. How much OJ does each person get?

One way to do it is you round the 1.36L to 1L. Then if you divide it by 4 it equals 0.25. Then if you get the .36 and divide it by 4 you get 0.9 and if you add that with the 0.25 you get 0.34L. So everyone will get 0.34L of OJ.
Picture of a number line

Monday, October 26, 2009

Dividing Decimals

Division: Division means that in the statement 5/2=3. There are three groups of 2 in the number six.

(:(: (:(: (:(: - 3 groups of 2 smiley faces.

The word Quotient is the answer to the division question.

If you have 6 dollars and you need pens for scrap booking that are 0.40 cents each?

We used 10x10 grids to solve this problem.

I did my grid like this :

(every colour represents a new type of pen.)
The number you could get with $6 is 15 glitter pens.

If you look at the two first pictures

= 5 glitter pens. and this is equal too $2 , 2 goes into 6 3 times. So, multiply the 5 x 3 = 15 glitter pens.

Now if you estimate, and make it an EASIER question, this is how you do it.
.40 round it off to 0.50 and round it to 2.

+2 - 2
4 -4
6 - 6
8 - 8
10 - 10
12 - 12

Where to put the decimal?


Round 3.6 to 4.
Now, change the question to a multiplication question.

Now divide the 16 by 4.
4 is nearer than 42. So put the decimal between the 4 and the 2.


This is a lady showing you how to divide decimals, if you need any help.

Tuesday, October 20, 2009

Multiplying Decimals

This is a blog of today's math notes.

How do you multiply by decimals? First we will look at dividing by .5

Multiplying by decimals is the same thing as dividing by whole numbers. But how is that possible?

If you multiply something by less than 1 you're going to get a smaller number than the number you are dividing by. 2x.5= 1. Its the same as 2 divided by 2.

eg. 46x2.5

Let's break it down.

40x2=80 6x2=12


Now we have the decimal part.

When you see x.5 it means to divide by 2

So 40 multiplied by .5 really means 40 divided by 2

40 divided by 2 equals 20

6 divided by two equals 3



So 46x2.5= 115

Here's a video that might help.

One thing the video brought up is that even though it looks like the answer is 3,864 you have to consider the numbers after the decimal point that hold value. In the equation the digits .1 and .4 are after the decimal point so you move the decimal point two places to the left. You will get 38.64 instead of 3,864.

I'm sorry about the fact that my keyboard doesnt have a divide button on it.

Remember: Math Links page 57-59 numbers 3-21 isn't homework

Here's an excellent link to a website that explains the concept of multiplying decimals well.


Monday, October 19, 2009

Estimating Decimals with Multiplication

This is a blog of today's notes and homework.

What is the total when estimating?

1.69 x5= Tax is included.

Younger sister says it only costs 5 bucks.

Older brother says it only costs 10 bucks.

What are they thinking, how are they estimating?

Younger sister is thinking Under estimating, just 1.00x5= $5.00

Older brother is thinking Over estimating, 2.00x5= $10.00

Where do the decimals go?
2.2 x 1.8= 3960

Where do the decimals go here?

3.9 x 5.8= 22620
Is $9.00 enough and prove it.

2.57 x 0.45= 118220

Pronghorn: 58kg Dall's: 1.5 times as much as a pronghorn.
How much does Dall's weigh?
Approximate: 90kg. 60x1=60 kg.
90 kg. (In between the two weights.)

60x2=120 kg.
Exactly: 87kg.

Homework is:

46x2.5 = 64x4.5 = First estimate then calculate.

Here is a video for multiplying decimals. If you click multiplying decimals it will take you to a link that explains the multiplying of decimals. Good Luck and I hope it isn't hard to understand.

Mr.Isfeld will be collecting number of the day tomorrow.

Friday, October 16, 2009

How To Scribe

This is a demonstration on how to scribe.

Link- highlight a word and press the green button. Then look for a site that you think would build interest and that is about the topic. Then you copy and paste the URL. After you get a link, click preview to check the link. Check out this link!

Image- find an image (google image) then save it to your computer. Then browse and find the image. You can change the layout and size. Then press upload image. See this image!

Video-Go to youtube and find a video that will build interest about the topic you are discussing. Once you've found a video, click on the grey box anf highlight and copy the code that is in the box titled "embed". Then click edit HT.ML. Scroll to the bottom then pick the code and press preview. See this video!:

Font-To change the font, click the arrow next to the word "font." Scroll down and find a don't that you like and that all can read.

Colour-To change the color, click on the T with the colored squares. Then choose a color. It is best to change the color of important facts, but try not to use bright colors that are hard to see.

Size- To change the size, click the sign with the double T's. Then change the size you want to write with. Don't pick anything too small or too large.

Room 43 first scribe

Here is our first blog.

Check out the link to the greatest team of all time.

Look at this image.
Or this video

Suzie will compose our first scribe on how to create a scribe.

Everyone else will leave a comment. You must leave something nice and something helpful.

Good luck and have a good weekend.