## Lower Secondary Mathematics

PSLE marks the graduation of Primary school students and their entry into Secondary schools as teenagers. Discuss all issues about Secondary schooling here.
iwork
BrownBelt Posts: 636
Joined: Fri Nov 07,
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### Re: Lower Secondary Mathematics

marstolive wrote:can anyone show me the solution for this question? C:
The HCF and LCM of two numbers, 12 and 5040 respectively. If one of the numbers is 144, find the other number.
Thanks HCF = 12 = 2^2 x 3
LCM = 5040 = 2^4 x 3^2 x 5 x 7

One of the number = 144 = 2^4 x 3^2

So, the other number must have 2^2 x 3 x 5 x 7 = 420

iwork
BrownBelt Posts: 636
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### Re: Lower Secondary Mathematics

YellowBelt Posts: 21
Joined: Tue Jul 10,

### Re: Lower Secondary Mathematics

Hi iWork

refer to my edited post

iwork
BrownBelt Posts: 636
Joined: Fri Nov 07,
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### Re: Lower Secondary Mathematics

Two race cars, car X and car Y are at the starting point of a 2-km track at the same time. Car X and car Y make one lap every 60s and every 80s respectively.
How long in seconds will it take for both cars to be back at the starting point at the same time?
Just find the LCM of 60 and 80, and that is the answer.

marstolive
BlueBelt Posts: 284
Joined: Sun Jan 30,

### Re: Lower Secondary Mathematics

iwork wrote:
marstolive wrote:can anyone show me the solution for this question? C:
The HCF and LCM of two numbers, 12 and 5040 respectively. If one of the numbers is 144, find the other number.
Thanks HCF = 12 = 2^2 x 3
LCM = 5040 = 2^4 x 3^2 x 5 x 7

One of the number = 144 = 2^4 x 3^2

So, the other number must have 2^2 x 3 x 5 x 7 = 420 marstolive
BlueBelt Posts: 284
Joined: Sun Jan 30,

### Re: Lower Secondary Mathematics

can someone help me with this?
Find the square root of 6x15x22x35x77 without using a calculator.
Thanks

Aberc
GreenBelt Posts: 171
Joined: Mon Oct 11,
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### Re: Lower Secondary Mathematics

marstolive wrote:can someone help me with this?
Find the square root of 6x15x22x35x77 without using a calculator.
Thanks
You need to express the numbers in terms of their factors, 3 x 2 x 5 x 3....., then group the common factors together, 2 squared x 3 squared x 5 squared x......, the square root of the squared factors will give you 2 x 3 x 5 x..... = ans.

Pepsi
YellowBelt Posts: 18
Joined: Fri Nov 23,

### Re: Lower Secondary Mathematics

Need HELP!!

Given that 360 = 2Cube x 3square x 5
a) the smallest integer, j, such that 360 x j is a perfect square
b) the smallest integer, k, such that 360 x k is a perfect cube
Find the j & k

iwork
BrownBelt Posts: 636
Joined: Fri Nov 07,
Total Likes:4

### Re: Lower Secondary Mathematics

Pepsi wrote:Need HELP!!

Given that 360 = 2Cube x 3square x 5
a) the smallest integer, j, such that 360 x j is a perfect square
b) the smallest integer, k, such that 360 x k is a perfect cube
Find the j & k
To get a perfect square, all the power must be even number.
To get a perfect cube, all the power must be multiple of 3.

So
a) j=2 x 5
b)k=3 x 5square

Pepsi
YellowBelt Posts: 18
Joined: Fri Nov 23,

### Re: Lower Secondary Mathematics iwork wrote:
Pepsi wrote:Need HELP!!

Given that 360 = 2Cube x 3square x 5
a) the smallest integer, j, such that 360 x j is a perfect square
b) the smallest integer, k, such that 360 x k is a perfect cube
Find the j & k
To get a perfect square, all the power must be even number.
To get a perfect cube, all the power must be multiple of 3.

So
a) j=2 x 5
b)k=3 x 5square