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Maths problem

helping out at school today we were doing a maths game  - its like the numbers game on Countdown.

You have 4 numbers and you have to use + - x / to get the answer 24

eg 6 4 7 7  you can say 6x4 = 24, and 1/1=1 and 24x1=24

now, we got the numbers 9 8 8 & 4 and I can't work out how to get 24

over to you brainboxes....

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• 4x8 =32 - 8 =24

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9-8 = 1

4-1 = 3

3 x 8 = 24

Is that what you mean?

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This ones a bit harder.

A cow is tied to the fence of a perfectly circular grass covered field.  How long would the rope have to be for the cow to eat exactly half the area of the field?

• Give the cow some scissors and let him cut the rope?
• 9-4 = 5

8-5 = 3

8*3 = 24

or all in one line (8  - (9-4))*8

• 9 x 4 = 36;   8+8=16 -4 =12 --------- 36-12=24

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It's a cow!
• Tut tut, online plagerism....

bend over.

• No you have to use all of the numbers

this isn't my homework, but it's annoying me that I couldn't work it out

JB - isn't that a how long is a piece of string type question

• Given that the cow doesn't have thumbs

Is the cow tied to the fence on the edge of the field or to a pole in the middle

Do you know anything about the size of the entire field?
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I did use all of the numbers?
• use all the numbers once

(and htese 11 yr olds aren't clever enough to use brackets yet!)

• Aha  - get you point Mouse!  yes that would work wouldn't it

vitual choccy on it's way to you

• Sharpen the cows teeth, put some grass on the rope, allow the cow to munch through the rope and then leave it aforementioned field to eat the grass.

Does that get past the no thumb problem?

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•  .

• Closest I've managed so far is 28.

• A bit longer than the distance to the centre, jb
• The cow problem
• That's what I said!

• wow
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I'm disappointed.  Did I say what side of the fence the cow was on?
• It' doesn't matter if you do the problem in 4 dimensional space
• 8 + 4 - 9 x 3 = 24

or am I too late!

I have a circular field (well paddock pen) and I have horse  ..... I am sorely tempted to go outside and try rope thing at lunchtime

• TP have you checked that?
• 9-8=1

4-1=3

3*8=24

yes?

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Ah shoot!  I read the question wrong.

I got  = [(r^2)/2]^(-1/2)

but that's if you tie the cow to the centre of the field.  I admit I couldn't work it out if I'd read the question properly.  I'm lame with Sin, Cos and Tan.

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Can RW put on a function that allows all threads with 'maths problem' in the title, cause an email to be sent to me?  I do love this kind of stuff, though to be fair, the first question was a bit easy (though if you're brain doesn't follow the right paths, you can get stuck on things like that for ages).
• Garr the soln to the cow problem is on my link further up the page
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