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Number and Algebra

Paiseh, pls help with 1 more. TIA!

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6

Darryl Seah

2 years ago

Yueh Mei Liu

2 years ago

Darryl Seah

Awesome. :-)

2 years ago

Lee Yuet Meng

Thank you!!!

2 years ago

Adrian Ng

2 years ago

Yeo See Yeong

Why am I still using algebra!!! Urghh...

2 years ago

Lee Yuet Meng

Asked 6 years ago

SG
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Primary 4
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Number and Algebra

Hello, anyone around to help. Is the answer 45? How to explain? What is the method to use other than counting? TIA!

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9

Michael Tan

10 teams. 1st team = 9 matches; second team play 8 matches; third team 7 matches...............10th team 0 match. Thus Total matches = 9+8+7+6+5+4+3+2+1 = 45 matches.

2 years ago

Lee Yuet Meng

I got 45 too. So it's simply by counting and adding. No models, tables or formulae?

2 years ago

Michael Tan

This is quite direct. Solve quite fast. Use simple ways to solve and save time. Don;t need model.
As every team will play with other teams. But in decreasing number in order to avoid repetition. This is the way to solve i believe. Fast and simple :)

2 years ago

Michael Tan

Can draw diagram to illustrate understanding...

2 years ago

Chia-Chan Bk

2 years ago

Hong Keng Kor

Agree with all above methods.
But is it not easier to consider tt there are 5 matches each round, and since each team needs to play agst 9 other teams, so total there are 9 rounds.
Answer will be 5 x 9 = 45

2 years ago

Pieter Cronje

Adding 1+2+3........9 can be done with adding it AGAIN. 1+9..2+8..3+7.....giving 10x9=90. But this must be halved...giving45. Einstein used this method of adding a series...

2 years ago

Pieter Cronje

It does introduce a series. Good example. A plays 9 games...B plays 8 (its. Game with A has been added) and carry on...then introduce the einstein trick! Kids will love it!

2 years ago

Pieter Cronje

2 years ago

Lee Yuet Meng

Asked 6 years ago

SG
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Primary 4
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Number and Algebra

Anyone can help? Thanks in advance.

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5

Choy Ban Heng

I used the same method as the one below. Hope it helps

$0.50 = 1 u
$0.20 = 1 u + 6
($0.50 x 1 u) - $0.20( 1 u +6) = $ 2.70
u = 13
13 x 0.50 = 6.50

2 years ago

Thit Mon Mon Win

$0.50 = 1 u
$0.20 = 1 u + 6
($0.50 x 1 u) - $0.20( 1 u +6) = $ 2.70
u = 13
a) 13 x 0.5 = $6.50
b) 13+6= 19

2 years ago

Michael Tan

Thanks All :)

2 years ago

Vera Koh

sorry for the "wordy" explanation. thought it may be clearer with the words.

2 years ago

Michael Tan

Thank U :)

2 years ago

Mohi Uddin Ahmed

Handwriting looks great too!

2 years ago

Choy Ban Heng

Here's another solution:

2 years ago

Vera Koh

Choy Ban Heng, $1.20 for Meimei is only 4x 30¢.. (even though it is 6x 20¢ coins for Sarah).
so, number of coins Meimei had should be 9 + 4 = 13.
this is a good model to see the 9x 30, but may result in careless mistake when comparing the $1.20 part cos the "u" for 20 is not the same length as the "u" for 30. :)

2 years ago

Choy Ban Heng

Here's the updated one. Thank you Vera Koh for pointing out the careless mistake. I think the problem could have been overcome if I have checked my typing and calculations.