Q&A - P4 Math

[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

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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

[MathIzzzFun]

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

Hi

Estimation is taught so that the children understand how to do approximation. Students will not be asked to provide estimate of say 246 x 39 without given the bounds. For eg. a better estimate for 246 x 39 is 240 x 40 but normally we will approximate it to 250x 40 (which will provide the upper bound).
Usually, choices will be provided for estimate of product of two numbers, or the question will specifically state whether the answer/number is to be rounded to 10 or 100. Ffor eg. Jenny had twelve stamp books with same number of stamps in each book. The total number of stamps Jenny had was 3500 when rounded to the nearest 10. How many stamps did Jenny have ?

cheers.

[chloecube]

Hi MathIzzFun,


i have got another similar question from the previous one i asked.

There are thrice as many children as adult in the park. if 57 adults leave the park, there will be 12 times as many children as the adults. how many children and adults are there in the park at first.

my answer is 304 using the method you have taught me

[MathIzzzFun]

chloecube:

Hi MathIzzFun,


i have got another similar question from the previous one i asked.

There are thrice as many children as adult in the park. if 57 adults leave the park, there will be 12 times as many children as the adults. how many children and adults are there in the park at first.

my answer is 304 using the method you have taught me

bingo !

cheers.

[HAPPYH]

HI Mathizzfun


You are a treasure to this forum. Thank you so much. Although my DD is in P3, I follow P4 Math as well. I copy and save for next year:)

[Xiao Hu]

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

Hi Tianzhu,
Thanks very much for your reply, appreciate it.

Yes, I looked at the P4 textbooks, the syllabus appears to be rounding off to hundreds. But the school is giving my son questions with values in thousands. So you are right, he can round it up to hundreds. That's what he did, and no wonder he did that.

Thanks,
Xiao Hu.