## 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

80+12=92

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

20+3=23

92+23=115

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.

http://www.mathsisfun.com/multiplying-decimals.html

1. Hm .. pretty impressive job Nils! I envy the perfect job. ;) The video made perfect sense, and I could read every single thing. Great job, Nils. Best I have seen so far. Nice one! :D

2. Good job! You added a picture, a link, and video that all made sense. You changed the colour of the important words, there were no mistakes (that I saw) so a big :) and four stars to you!

3. Good job! The video you chose was really good and very easy to understand.The picture was a good choice as well as the website link. Great job and very neat!

4. Good Job Nils!!You did a good job with explaining where to find the where the decimals are.Nice video and picture.Im sure you're mom will be proud with you:)

5. Good Job! You added everything that it needed, now I know what I missed for today.
Thanks Nils,you did an awesome job!:)

6. GREAT JOB! I really liked that you explained some of the things that were in the video. When you were explaining how multiplying a decimal is just like dividing I thought that it was very easy to understand and also was your example. But next time maybe try to find more pictures that would help explain, like a picture that had arrows showing where the decimal had moved to and how far it moved. But overall, you did a FABULOUS job! Keep up the good work! :D

7. Good job. I liked the video because it's helpful and I like how you changed the colour of the important words.

8. Whoa! Nice joooooooooooooooooooooob Nils! Your work is very spread out so it is easy to read, you explained pretty well and you really seem like you knew what you were talking about. Next time, try to get a bigger picture. Also try changing your font of important words different colors, other than red. I think that would really pop out more. Other than that, awesome scribe (:

9. Great job! You explained everything thoroughly and carefully. I liked how you changed the color of important words because it really makes sure anybody who reads it will pay extra attention. I also really liked your video because it is very helpful to anyone who doesn't yet understand the concept of multiplying decimals. Very good! Keep it up!

10. Good Job! Nils, i like how you said that dividing decimals and multiplying decimals. I do agree with kristel. I liked it when you explained stuff in the video. Excellent Job! Nils ill give you 2 thumbs up!

11. Great job! I like how you explained very carefully how to multiply decimals, and I'm glad that you demonstrated how to do it. You included everything we did today.You also had a great video, picture and link. It explains the topic perfectly.

12. Good Job Nils, this really helped me. I was kind of freaking out for a while if pages 57-59 for homework until I saw this scribe. Anyways, I really liked how you used the red color font to show that it's really important to know. I really liked how you chose this video, and I think from the old blogspot for 08. I remember seeing some person posting that very same video. Well, EXCELLENT JOB NILS. KEEP IT UP (:

13. Good job Nils! I like the video you posted. It was helpful. It was easy for me to copy down the notes when I went home. Great Job! :)

14. good vedio it was very clear on what you were saying know it makes a lot more scince to me.

15. i like the video you had on the blog. the things you sayed made sence.

keep it up.XD!!

^__^

16. Good Job!!!!!!!!!!!!!!!!!!! I really liked it

17. Good job Nils! It was really nice I think it kinda helped me. Nice video by the way and nice picture!

18. Good job Nils you picked a really good good video. I really liked your video. Now I know how to do multiplying decimals. If you could change it explain more. That wold be GREAAAAAAAATTTTTTTTTTTTT!!!!!!!!!!!!!!!!

19. Gooood job!!! nils i really liked how you explaned mutyplying decimals. You made a pretty good staemeant on how mutypliing decimals is like dividing. Loved your vedio.

20. GOOD JOB NEILS!!You did awesome on every thing and I have nothing to say about your post.So ya Goo Job And keep the goo work up!!!!..!!!!

21. GOOD JOB NEILS!! you show how you can to multiply decimals

22. GOOD JOB NEILS !!!!! you show that you can multiply decimals