Math Is Fun Forum

em1987

Guest

Decimal quiz..

Im completeing a problem book for uni and i have been stumped my this seemingly simple question.

'I am thinking of a number, If i divide 10 by my number u get 25. what is my number?

Explain why my number is NOT 250?'

any help would be much apreciated

TheDude

Member

Registered: 2007-10-23

Posts: 361

Re: Decimal quiz..

You have it backwards.  You're solving x/10 = 25, when it's asking for 10/x = 25.

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Wrap it in bacon

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Decimal quiz..

Hi em1987;

Call the number you are thinking of n. Now it says,

If i divide 10 by my number

So you get,

Solve:

Welcome to the forum!

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

em1987

Guest

Re: Decimal quiz..

thank you! that was so fast and so helpful!!

you are both amazing

em1987

Guest

Re: Decimal quiz..

Seeing you are so amazing, i have another one for you .

turn these terminating decimals into fractions.

A)   0.875

B)   0.0875

For that one i worked out A) by realising that it was .125 away from being one, and then divding 1 by .125 and getting 8. I know think that  the fraction for A) is 7/8
But i dont know how to write it from B)

C)    0.4375

D)     0.04735

This second part has me stumped as my method for working out A) hasn't worked here..

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Decimal quiz..

Hi;

A) 7 / 8

B) 7 / 80

C) 7 / 16

D) 7 / 160

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Decimal quiz..

hi em1987,

Back in the dark ages, when I was a little boy in short trousers, my teacher taught me this rule.  As I can still remember it, she must have been good!

Put a one under the decimal point and a zero for every figure after that.  Rub out the leading zero(s) and the point and you have a fraction.  You may need to cancel it down.

eg.  0.875 = 875/1000 = 175/200 = 35/40 = 7/8

eg.  0.04735 = 4735/100000 = 947/20000

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob