Very tricky maths problem for 10 year old?

[robinia]

Dd, along with selected others of her class, has been given a maths problem which I can't work out and nor can dh:

Using numbers 2, 4, 6 and 8 and "divided by" and "equals", make every number from 1 to 32.
eg. 1 = 8 divided by 8; Can't use plus, minus or multiply. Can use each of the numbers as many times as necessary.

We can only get about 1/4 of the answers. Can anybody enlighten us and isn't this a bit tough for a 10year old or is this the way they teach maths these days?

Asked DH, and he says, no, not possible. Having / and () gives you *, essentially. But not anything else. So there's no way to get in any primes that aren't there already. You've only got 2 and 3 there.

6/4= 1.5 4/8 =.5
48/ (4/8) =
48/.5 =19

F* my ds is clever

22/1.5 =17

wow I am impressed

me too the maths brain skipped a generation
He is a maths genius as it happens but I thought this would tump him as it stumped dp who is a physics graduate!

except 48/0.5 = 96 (by my calculator)

& 22/1.5 = 14 2/3

or isn't it?

I've sent him to bed now but will grill him in the morning... cocky little sodling!
I would not know the answers

Slow brain here but did he get the 48 and the 22 by combining the digits, Piffle? Dd is adamant that's not allowed.

Think I've got a couple more:

18 = (6/2)/ (2/6)/ (2/4)
27 = (6/2)/ (2/6)/ (2/6)

Does that make sense ...?

How can you use .5 when the only numbers allowed are 2, 4, 6 and 8??

so is 20

6/3 / 2/4 / 2/6?

You get .5 by doing 2/4. That's easy enough.

But I'm not sure how you get primes, still.

Katymac, your last example makes 12, I think.

Oh, and yeah, robinia, those look good, but don't solve the underlying primes problem. You're still just playing with 2s and 3s.

Perhaps the isntruction was to use the digits, not the numbers, eg 7 = 28/4

Sorry - just realised that several others suggested that. However I cannot believe that a 10-year old woudl be expected to use nested operations such as 4/(1/8) or 4/((8/8)/8).

if you can get 10
you can 10/8 =.8
4/ (10/8) = 5
4/.8 =5

I meant 8/10 even!!!!!!!!!!
D'oh

I've had an extensive play with this and I really don't think that you can get anything other than

2/2 = 1
2 = 2
6/2 = 3
4 = 4
6 = 6
8 = 8
6/(4/6) = 9
8/(4/6) = 12
8/(2/4) = 16
(6/(4/6))/(2/4) = 18
6/(2/8) = 24
(6/(4/6))/(2/6) = 27
8/(2/8) = 32

using the numbers as numbers rather than digits. If you set up all the possible permutations of "divided by" and iterate it, all you get is these numbers (plus some higher numbers) over and over again. I'll be fascinated to see the answer if I'm wrong.

But Piffle, we can't get 10. We can't get anything that's made out of anything but 2s and 3s.

this has bugged me alllllllll day long and I don't think it is possible with just a divide (even with brackets) to get numbers which are a factor of 5 and the prime numbers

Hello - just found this thread. I was a maths teacher b4 having my boy. My mother has been a primary maths teacher trainer for 40 years and my sister has a doctorate from oxford in material sciences.

I have just spoken to my mum and told her the problem, she is with my sister & they love a challenge. She is focussing on primes.

I am now going to have a go myself.

Hope we can provide answers - if not then ??!!??

Ok, I've got 5.

I can't believe this was given to a 10 year old!

You can use mulitiplication as well as division because multiplication is the same as dividing by 1/?

I mean that (1/4)/2 = 1/4 x 1/2.

This is quite complicated, I hope it comes out alright on screen.

I'll do it in stages...

2/6 = 1/3

(1/3)/4 = 1/20

(2/2)/(1/20) = 20

20/4 = 5

From this working we can get all the multiples of 5.

What else do we need?

Um. (1/3)/4 = 1/12. Doesn't it?

S**t
I put this down to early pregancy!
back to the drawing board