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**JayWalker****Member**- Registered: 2006-02-07
- Posts: 4

Can someone please help me?? I'm a Mum trying to help my son with his maths homework, and I'm not much of an Einstein. I just CAN'T figure out how to calculate 7% of 9%.

Doesn't even make sense to me!!!!

I'd be eternally grateful if someone could explain this to me. Many thanks in advance!!!!

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**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

Convert the percentages into decimal numbers by dividing by 100.

"Find 0.07 of 0.09"

Then just multiply the two together. 0.07x0.09 = 0.0063

Then multiply by 100 to convert back into a percentage:

"7% of 9% is 0.63%"

A quicker way would be to just multiply the 2 percentages together, then divide by 100.

Why did the vector cross the road?

It wanted to be normal.

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**Ricky****Moderator**- Registered: 2005-12-04
- Posts: 3,791

I'm a Mum trying to help my son with his maths homework, and I'm not much of an Einstein.

And it's a good thing too. Didn't he fail math?

"In the real world, this would be a problem. But in mathematics, we can just define a place where this problem doesn't exist. So we'll go ahead and do that now..."

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**kempos****Member**- Registered: 2006-01-07
- Posts: 77

7% of 9% = 7/100 of 9/100 = 7/100 * 9/100 = 63/10000

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**JayWalker****Member**- Registered: 2006-02-07
- Posts: 4

Thank you so much everyone!!!!

I don't understand why one has to multiply the two percentages, but I will take your word for it!!!

I really shouldn't be helping my son. As he told me yesterday: "Mom, I'm capable of making mistakes all by myself!!" - LOL!!!!

It's very frustrating though not to be able to help him. Maths causes him quite a lot of problems at school - it's really the subject where he struggles the most, and he just cannot STAND his teacher who he has had unfortunately for two years now. If he has him next year, it's going to be a disaster!!!!

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**justlookingforthemoment****Moderator**- Registered: 2005-05-26
- Posts: 2,161

JayWalker wrote:

I don't understand why one has to multiply the two percentages, but I will take your word for it!!!

You multiply the two percentages together because when you see **of**, as in 1/2 **of** 20, it is the same as multiplying. So 1/2 of 20 is the same as 1/2 x 20, which equals 10.

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**JayWalker****Member**- Registered: 2006-02-07
- Posts: 4

Thank you Winked. I understand now!!!

I have one more question actually, and then I'm through hopefully.

How does one calculate 2/3rds of 7/9ths?

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**justlookingforthemoment****Moderator**- Registered: 2005-05-26
- Posts: 2,161

In the same way as before. Just this time it's with fractions.

Multiply the numerators (the numbers above the line) together and the denominators (below the line) together, like this:

Which can then be simplified as shown above. So, 2/3 of 7/9 equals 2/21.

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**kempos****Member**- Registered: 2006-01-07
- Posts: 77

to simplify means to divide denominator and denominator by the same number :-)

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**JayWalker****Member**- Registered: 2006-02-07
- Posts: 4

Yay!!!! I've got it.

Cool. Thanks a million!!!!!!!

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