Q&A - P4 Math

[chloecube]

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

[Nebbermind]

alan000:

http://i42.tinypic.com/69p8jk.gif\">

cmm:

Sue has more than 50 hairpins.

If she puts them in packets of 7, she has 5 hairpins left.
If she puts them in packets of 9, she has 6 hairpins left.
How many hairpins does Sue have?

Dear cmm,

Hope this helps.

Are there any other method of solving this qn? Like using models?

[MathIzzzFun]

chloecube:

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://www.flickr.com/photos/62167097@N02/6773560540/in/photostream

cheers.

[chloecube]

MathIzzzFun:

chloecube:

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://i41.tinypic.com/jfxkle.jpg\">

cheers.

thks MathIzzzFun,
but i do not quite understand why you only drew 2 units in the 2nd model since James has thrice as much as Alex after the $50 spent.
shldnt it be 3 units instead?

Thks

[chloecube]

chloecube:

MathIzzzFun:

[quote=\"chloecube\"]hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://i41.tinypic.com/jfxkle.jpg\">

cheers.

thks MathIzzzFun,
but i do not quite understand why you only drew 2 units in the 2nd model since James has thrice as much as Alex after the $50 spent.
shldnt it be 3 units instead?

Thks[/quote] :oops: okok, i think i got it, thks!!!

[HAPPYH]

MathIzzzFun:

chloecube:

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://i41.tinypic.com/jfxkle.jpg\">

cheers.

Nice explanation. Thank you so much.

[chloecube]

Thank you all for the help rendered, esp to tian zhu and mathIzzzFun!

i am going :siao: with DS's heuristic math, but i have the kick if i managed to solve them, and :faint: if i am stuck.

Thks everyone

[Xiao Hu]

Hi Tianzhu, MathIzzzFun,


I have some questions on "estimation" that I hope you can help answer. I did a search with "estimation" but after going through 4 pages that don’t have anything relating to my question, I decided to ask it here.

The question did not say estimate at which digit or which value.
Estimate 7281x39.
I think of 2 possible way to estimate
(1) ~7300 x 40
(2) ~7000 x 40
Mentally, it’s so much easier and quicker to say (2) is a "better" estimation.

Anothe example:
Estimate 246 x 39
(1) ~250x40
(2) ~200 x 40

What’s the rule or rules to teach our children when it comes to estimating?

TIA,
Xiao Hu

[jedamum]

Xiao Hu:

Hi Tianzhu, MathIzzzFun,


I have some questions on \"estimation\" that I hope you can help answer. I did a search with \"estimation\" but after going through 4 pages that don't have anything relating to my question, I decided to ask it here.

The question did not say estimate at which digit or which value.
Estimate 7281x39.
I think of 2 possible way to estimate
(1) ~7300 x 40
(2) ~7000 x 40
Mentally, it's so much easier and quicker to say (2) is a \"better\" estimation.

Anothe example:
Estimate 246 x 39
(1) ~250x40
(2) ~200 x 40

What's the rule or rules to teach our children when it comes to estimating?

TIA,
Xiao Hu

xiaohu,
i faced this problem too. my boy used the easier method. he checked with his teacher who said she would not be testing on this as both are methods of estimation, so cannot said which is wrong since nothing is said on estimate to nearest tens or hundreds.

let's see what others have to say.

[tianzhu]

Xiao Hu:

What's the rule or rules to teach our children when it comes to estimating?

Hi

I am sorry; I am a post PSLE dad and have not been actively reading up primary school maths for some time. So I might not be in an appropriate position to answer your query.

Estimation is the process of finding an approximate answer to a numerical problem.

We often need to estimate or “agar agar” in our daily life.

For example, we estimate the amount we need to pay for our groceries in the supermarket to ensure that the cashier charge us correctly.

Different methods of estimation often give different estimated values.

If I am not wrong, rounding off to hundreds only is covered in P4 syllabus.

My advice here is to study the examples given in the textbooks so as to study the requirements as expected in the syllabus.

Best wishes