Year 6 Maths!
24 March 2004, 06:51 PM
#1
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Year 6 Maths!
I know, it's way OT, and a man of my years ought to know how to do it, but my 10 year old has asked for help on this:
There are eight doors in a row. Behind each door is a number. Each number is less than 20. No two numbers are the same, and the numbers on the doors are in order.
Three of the numbers are prime numbers.
Two of the numbers are multiples of 5.
Two of the numbers are square numbers.
Five of the numbers are even.
Three is a factor of two of the numbers.
There are a pair of consecutive numbers, and four consecutive numbers on the doors.
The sum of the numbers is 93.
What are the numbers on the doors??
There must be a straightforward way of working this out, more logical than bunging numbers in and guessing, but I'm buggered if I can see it.
Anyone??
There are eight doors in a row. Behind each door is a number. Each number is less than 20. No two numbers are the same, and the numbers on the doors are in order.
Three of the numbers are prime numbers.
Two of the numbers are multiples of 5.
Two of the numbers are square numbers.
Five of the numbers are even.
Three is a factor of two of the numbers.
There are a pair of consecutive numbers, and four consecutive numbers on the doors.
The sum of the numbers is 93.
What are the numbers on the doors??
There must be a straightforward way of working this out, more logical than bunging numbers in and guessing, but I'm buggered if I can see it.
Anyone??
24 March 2004, 07:37 PM
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Thats a proper b'stard to work out!!(looks easy too)
Tell the teacher where to shove his h/wk!
EDIT - Is bextait havin' a larrf? Yer 30 numbers out luv
Tell the teacher where to shove his h/wk!
EDIT - Is bextait havin' a larrf? Yer 30 numbers out luv
Last edited by chaos.; 24 March 2004 at 07:54 PM.
24 March 2004, 07:56 PM
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The answer has to be in what your son's been studying in the last two weeks or so. They aren't given brain busters like that just as the teacher's a ****.
Hmm, on the other hand...
Hmm, on the other hand...
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24 March 2004, 08:04 PM
#9
bloody hell!! 
That's more like secondary school stuff!
Just for the challenge I worked it out as:
4 5 8 10 15 16 17 18
How?
well, 1st wrote down all the primes, then multiples of 5, squares, evens, and factors of 3 between 20
Now this took some guessing and logical stuff, but..heres my way:
Realising 5 of them had to be even and 3 were primes, you can assume that 3 will be odd.
I then took the multiples of 5 5 and 15, crossing them off my primes (1 left) so all but 1 are now even.
I took the two squares: 4 and 16, know they will have to be used (need 5 evens don't you)
noticing I needed another factor of 3 (already have 15) I picked 18..beacuse it was even.
this is now so far: 4,5,15,16,18
So need 3 more, noticed that 4 were consecutive..and needed another prime number, so I picked 17. (to make 15,16,17,18)
So needed two more...added them all up and took away the required sum, and noticed I needed 18...so this is where I guessed
two even number....10 and 8
done...in a very roundabout manner...took a while too! I must be going senile
There has to be a better way!
That's more like secondary school stuff!Just for the challenge I worked it out as:
4 5 8 10 15 16 17 18
How?
well, 1st wrote down all the primes, then multiples of 5, squares, evens, and factors of 3 between 20
Now this took some guessing and logical stuff, but..heres my way:
Realising 5 of them had to be even and 3 were primes, you can assume that 3 will be odd.
I then took the multiples of 5 5 and 15, crossing them off my primes (1 left) so all but 1 are now even.
I took the two squares: 4 and 16, know they will have to be used (need 5 evens don't you)
noticing I needed another factor of 3 (already have 15) I picked 18..beacuse it was even.
this is now so far: 4,5,15,16,18
So need 3 more, noticed that 4 were consecutive..and needed another prime number, so I picked 17. (to make 15,16,17,18)
So needed two more...added them all up and took away the required sum, and noticed I needed 18...so this is where I guessed
two even number....10 and 8done...in a very roundabout manner...took a while too! I must be going senile
There has to be a better way!
Last edited by ALi-B; 24 March 2004 at 08:07 PM. Reason: 17 not 14 ;)
24 March 2004, 08:07 PM
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Kinda how I did it ali, tho I forgot about the total 
I agree that it is difficult tho!
I agree that it is difficult tho!
24 March 2004, 10:56 PM
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Originally Posted by SteveLegacyToo
Lord only knows, Krazy!
It was just a thought.... spend ages trying to work it out only to be told there are no numbers on the doors.... or something to that effect...
24 March 2004, 11:23 PM
#21
OK OK, it's
4, 6, 10, 11, 14, 15, 16, 17
I think that's it.....no methods, just what I did above and I swapped some numbers about to suit.
This wouldn't happen to be anything with the use of trial and error....sorry what do they call it these days? I think the PC lot changed it to "trial and improvement" but they may have changed it again
4, 6, 10, 11, 14, 15, 16, 17
I think that's it.....no methods, just what I did above and I swapped some numbers about to suit
.This wouldn't happen to be anything with the use of trial and error....sorry what do they call it these days? I think the PC lot changed it to "trial and improvement" but they may have changed it again
25 March 2004, 10:57 AM
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ALi-B
I think that sequence only has 2 prime numbers, not 3!
My attempt is
1 2 10 14 15 16 17 18
But I'm not sure how that fits in with the wording
"There are a pair of consecutive numbers, and four consecutive numbers on the doors."
So is probably wrong as well!
Ratman
I think that sequence only has 2 prime numbers, not 3!
My attempt is
1 2 10 14 15 16 17 18
But I'm not sure how that fits in with the wording
"There are a pair of consecutive numbers, and four consecutive numbers on the doors."
So is probably wrong as well!
Ratman
25 March 2004, 04:11 PM
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quite shocking that nobody has been able to do a 10 year old's homework. you all ought to be ashamed of yourselves!
the teacher is either taking the ****, or looking for geniuses, because theres no way 99.999% of 10 year olds would be able to do that.
oh yeah, the answer is: 2, 4, 10, 11, 15, 16, 17, 18
milo
(not 10 years old, but waiting to be corrected)
the teacher is either taking the ****, or looking for geniuses, because theres no way 99.999% of 10 year olds would be able to do that.
oh yeah, the answer is: 2, 4, 10, 11, 15, 16, 17, 18
milo
(not 10 years old, but waiting to be corrected
)
25 March 2004, 04:32 PM
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Originally Posted by milo
quite shocking that nobody has been able to do a 10 year old's homework. you all ought to be ashamed of yourselves!
the teacher is either taking the ****, or looking for geniuses, because theres no way 99.999% of 10 year olds would be able to do that.
oh yeah, the answer is: 2, 4, 10, 11, 15, 16, 17, 18
milo
(not 10 years old, but waiting to be corrected)
the teacher is either taking the ****, or looking for geniuses, because theres no way 99.999% of 10 year olds would be able to do that.
oh yeah, the answer is: 2, 4, 10, 11, 15, 16, 17, 18
milo
(not 10 years old, but waiting to be corrected
)http://www.standards.dfes.gov.uk/num...t11spr_res.PDF
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