Q&A - P3 Math

[ammonite]

sembgal:

vinegar:

Mary thinks of a 2-digit number.When the number is divided by 5, the remainder is 3.When the number is divided by 9, th remainder is 1. What is the number?

The answer is 40.
Working: 5 + 3 = 8
9 + 1 =10
The first common multiple of 8 and 10 is 40
8, 16, 24, 33, 40
10, 20, 30, 40

? 40 divided by 5 is 8, no remainder leh.

I don't know what the standard method is, but through deduction, my answer is 28.

[vinegar]

vinegar:

Mary thinks of a 2-digit number.When the number is divided by 5, the remainder is 3.When the number is divided by 9, th remainder is 1. What is the number?

Anyone? How to teach? Is there a modeling? :?:

[sembgal]

ammonite:

sembgal:

[quote=\"vinegar\"]Mary thinks of a 2-digit number.When the number is divided by 5, the remainder is 3.When the number is divided by 9, th remainder is 1. What is the number?

The answer is 40.
Working: 5 + 3 = 8
9 + 1 =10
The first common multiple of 8 and 10 is 40
8, 16, 24, 33, 40
10, 20, 30, 40

? 40 divided by 5 is 8, no remainder leh.

I don't know what the standard method is, but through deduction, my answer is 28.[/quote]Sorry, mistake on my part. Thanks for highlighting to me.
Working:
For Groups of 5 with remainder 3
5, 10, 15, 20, 25
If add 3= 8, 13, 18, 23, 28

For Groups of 9 with remainder 1
9, 18, 27
If add 1= 10, 19, 28

The answer is 28

[vinegar]

thanks sembgal…


will be great if there is someone able to modelize it

[vinegar]

another question:


Lynn has a box of 153 buttons.If she needs another 7 buttons so that every blouse she sews can have 5 buttons, how many blouses has she sewn?

[sembgal]

vinegar:

another question:


Lynn has a box of 153 buttons.If she needs another 7 buttons so that every blouse she sews can have 5 buttons, how many blouses has she sewn?

153 + 7 = 160
160 / 5 = 32
Answer: 32 blouses

[ammonite]

sembgal:

vinegar:

another question:


Lynn has a box of 153 buttons.If she needs another 7 buttons so that every blouse she sews can have 5 buttons, how many blouses has she sewn?

153 + 7 = 160
160 / 5 = 32
Answer: 32 blouses

I thought she wants to sew 32 blouses but has only sewn 30 since she still needs 7 buttons. How to interpret the question?

[sembgal]

ammonite:

sembgal:

[quote=\"vinegar\"]another question:


Lynn has a box of 153 buttons.If she needs another 7 buttons so that every blouse she sews can have 5 buttons, how many blouses has she sewn?

153 + 7 = 160
160 / 5 = 32
Answer: 32 blouses

I thought she wants to sew 32 blouses but has only sewn 30 since she still needs 7 buttons. How to interpret the question?[/quote]Hi Ammonite, yes. Thanks for pointing out to me.
153 + 7 = 160
160 / 5 = 32 blouses
7/5=1R2 ~ 2 blouses
32 - 2 = 30 blouses.
Yes, shortage of 7 buttons, therefore has to reduce by 2 blouses.
Therefore she has sewn 30 blouses

[ammonite]

sembgal:

Hi Ammonite, yes. Thanks for pointing out to me.
153 + 7 = 160
160 / 5 = 32 blouses
7/5=1R2 ~ 2 blouses
32 - 2 = 30 blouses.
Yes, shortage of 7 buttons, therefore has to reduce by 2 blouses.
Therefore she has sewn 30 blouses

Is it possible to just take 153 and divide by 5 to get the answer? She has sewn 30blouses with 3 remaining buttons.

The extra 7 buttons seem to be just a red herring to me.

[sembgal]

ammonite:

sembgal:

Hi Ammonite, yes. Thanks for pointing out to me.
153 + 7 = 160
160 / 5 = 32 blouses
7/5=1R2 ~ 2 blouses
32 - 2 = 30 blouses.
Yes, shortage of 7 buttons, therefore has to reduce by 2 blouses.
Therefore she has sewn 30 blouses

Is it possible to just take 153 and divide by 5 to get the answer? She has sewn 30blouses with 3 remaining buttons.

The extra 7 buttons seem to be just a red herring to me.

I suppose yes because the answer can be derived from quotient. Children need to use the method that they understand.