Monday, November 1, 2010

Dividing decimals using estimation

What we did was:

Pens cost $0.40

You have $6.00

Estimate how many pens you can buy.

Change the $0.40 into $0.50 then its $6.00 divided by $0.50 = 12
If you calculate $6.00 divided by $0.40 it equals 15.


We used 10 by 10 grids to find out what the answer was and if there were 6 of these we shaded in 4 lines and filled in all of the 6 10 by 10 grids and we counted how many 4 shaded lines and there was 15.


The other thing we did was:

Place decimals in the answer by estimating.

a) 15.4 divided by 3.6 equals 427778

b) 4.4 divided by 0.42 equals 1047619

For a) make the 15.4 into 15 and the 3.6 into 3 then its now 15 divided by 3 equals 5.
Then put the decimal between the 4 and the 2 like this 4.27778.

For b) change the 4.4 into 4 and the o.42 into 0.40 because if you change it to 0 it wont have an accurate answer. 4 divided by 0.40 equals 10 so put the decimal between the 0 and the 4 like this 10.47619.

0.4 4 40 400 it is like multiplying by 10 so for example 0.4 x10= 4 x10= 40 x10= 400 and so on.
If it is backwards it is dividing by 10 so 400 ÷10= 40 ÷10= 4 ÷10= 0.4.

The final thing we did was:

Some people use 1, 2, 10, 11, 12, 20, 21, 22, 100 because they don't know 3, 4, 5, 6, 7, 8, 9.

Place the decimal in the answer by estimating.


a) 20.1 ÷ 4.7 = 42766


b) 3.5 ÷ 0.213 = 164319

Make the 3.5 into a 4 and the 0.213 into a 0.2 for b). 4 ÷ 0.2 = 20 16.4319

Make the 20.1 into a 20 and 4.7 into a 5 for a). 20 ÷ 5= 4 4.2766















34 comments:

Jason 8-73 said...

Hi this is Jason. I liked that you split all three subjects. A link you could use for your scribe is http://www.gamequarium.com/decimals.html
Something else you can do is put the answer in the final subject. I hoped I helped you with this info. Bye :)

kassey814 said...

i think it explained everything that we did in math class, I like the picture because it was the same picture as in class,the a and b answers that you put was very helpful to me good job.

Kamille817 said...

I really like your post here, Jamodin. It'll remind us what we did today at math. When you estimated how many pens you can buy, you could've also said what kind of estimation you used like Front end, Relative Size, Over or Under Estimation. Anyway, Good Job and Thanks a lot for all the reminders.

Lance873 said...

I really like your post Jamodin but it would help if you put a video on it. Good Job

madeline816 said...
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Diana814 said...

Hi Jamodin. I like it how you put exactly what we did in class.But I think you should read your post before you put it up. Also you should add a game or a video. Here is a link that I found on the internet. I didnt find other games because the games didnt work. Good Job!

madeline816 said...

I like your post, but it would help us more if you a link, and a video.

Anonymous said...

I understand how we estimate and divide decimal numbers. I liked the part where you said, some people use 1, 2, and 10 because they don't know 3, 4, and 5.

Danilyn8-73 said...

I think you did a good job with this post, but insert a video/link just in case to make sure other people understand. Also, maybe instead of putting the "other thing" maybe you could just put "second of all", just an advice.

abby873 said...

goodjob jammy (: this really helped me on what I have to catch up on today and what I need to understand about dividing decimals more. this really helped and you really made it easy for me to understand (:

hannah816 said...
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hannah816 said...

hi Jamodin. Good job on the post. This reminds me of what we did in math today. I think it would help more if you added a little game we can play to practice decimals like this one ; http://www.math-play.com/decimal-math-games.html

aaron873 said...

Hi this Aaron Lapuz. Jamoodin this really helped me a lot it shows exactly what we actually did in math. I also like the picture it really looks a like to ours. I also really like the numbers that you put for the people who didnt know the other numbers. Thanks Jammy :)

ronalen 8-14 said...

the scribe post really explains what we did in class today.It would really help the people who were away. good job

Sompong8-17 said...

Hey, I like the fact that it refreshed my memory and reminded me about everything we did in class today. When you were explaining, you did well at being detailed with your words. Good job, Jamodin.

Michael711 said...

Hi Jammy. I like your post and how you split it up in 3 sections, it made it a lot easier to read. But you could have been more creative with the sub titles, e.g. The first thing we worked on was:

or; Something that I had trouble with was:

irena814 said...

Hi Jamodin, good work on the post! It shows what we did in math today. I think that next time, you should put a link to a game or a video to explain more about estimating and multiplying decimals. So here are some links to some math games on rounding and multiplying decimals! Thanks Jamodin!

http://www.ixl.com/math/practice/grade-7-round-decimals
http://www.ixl.com/math/practice/grade-7-multiply-decimals

serena 814 said...

Jaomdin, I like the way you showed what we have learned today in class. But next time you should add a link to a game or a video to explain more about the topic. Here is a link on estimating decimals.
http://www.ixl.com/math/practice/grade-7-estimate-sums-differences-and-products-of-decimals
Thank-you for making a scribe post!

randolph814 said...

Hi. I like your post. Bye! :-)

Cindy814 said...

Hi,I like your scribe post,but I think the picture will look more like what we did in class if you color it.Good Job Jomodin!

melody711 said...

Very good job this shows everything we did in class but maybe you can use a LINK but still good job.

beverly814 said...

Great job Jamodin, I really liked how you explained everything that we did in class today. It refreshed my memory on how to estimate and divide decimals. I think you should have put more on the picture. Good job!! :)

Sarah7-11 said...

Great job Jamodin, I really liked your scribepost, but instead of putting "the other thing" I think you could put "first we did this". You should put a video of a teacher showing how to do this stuff. You should also put a link to show how to estimate.

Nathan711 said...

Hey Jammy great post I like how much you wrote. It really helped me to have an understanding about everything. But you could of found a more detailed picture=0

kristan817 said...

hey jam i liked how u said the stuff it helped me alout,but you could'v put a pic.:)

kristan817 said...

hey jam i liked how u said the stuff it helped me alout,but you could'v put a pic.:)

kristan817 said...
This comment has been removed by the author.
Anonymous said...

thanks Jamodin this really helps me because I wasen't here yesterday so thanks again.

Joshuarego814 said...

This was a pretty good scribepost, but I think you could have used a picture.

philip7 said...

i like your blog its so cool

steven711 said...

nice job that pretty much couvers it but one suggestion it would be better if u added a video :) =)

Diana814 said...

Hi Jammy!! I think you did a great job! Next time I think you should put a video or a website. Heres a game that I found on the internet. http://cemc2.math.uwaterloo.ca/mathfrog/english/kidz/order.shtml

Chelese711 said...

this post really helped me understand how to divide decimals useing estimation.one way to improve is adding a video

jairusa873 said...

Good Job it helped me. I forgot we did the 10x10 grid and I dind't even know what to do with the qestion.