Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

Use number 8 6 times to make 1000.

You can only use +, -, *, /, square root and parenthesis ().

No factorials, 3rd root or any other numbers.

Thank you!!!

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,676

Hi anna_gg;

Welcome to the forum! Do you know whether this has an answer or not?

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

Offline

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

It does, but I don't know it! All my attempts end up in using 7 8's or more!

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,676

Yes, there are lots of solutions for 8 8's and perhaps for 7 8's also. But I have never seen one for 6 8's.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,393

hi anna_gg and bobbym

I've got some 7 eights solutions. But 6 is still eluding me.

Bob

The five weighings problem is getting very complicated.

I'm doing things like balance 2 unknowns against 1.

If they balance then they must be (10,20,30) or (10,30,40) or (10, 40,50) or (20,30,50)

If the two go down then (10,20,40) or (10,20,50) or (10,30,50)

If not then there's loads of possibilities eeekkk.

Depending on which, try other balance possibilities.

The total map of alternatives is very large!

OR

(Im)Balance any pair and call them v and w so that v<w

(Im)Balance another pair and call them x and y so that x < y.

Then try w against x. Again lots of possibilities.

Cannot find a simple, elegant way to tackle this.

*Last edited by bob bundy (2012-01-11 03:12:06)*

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,393

hi anna_gg

Bob

*Last edited by bob bundy (2012-01-11 07:11:21)*

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

We are only allowed to use decimals in the form 8.8, not .8, as this assumes leading zeros

Otherwise, another like that would be 888/.888.

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,393

hi anna_gg

Please would you post the exact wording in the original question.

I'm 'clutching at straws' now.

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,676

Hi;

I have done a large computer search for some answer, also a search of the available literature for these type problems. I am coming up dry.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

Offline

**benice****Member**- Registered: 2010-06-10
- Posts: 110

1000 = 10^3

10 = 8 + sqrt( sqrt(8+8) )

3 = sqrt(8 + 8/8)

*Last edited by benice (2012-01-12 02:22:58)*

My Gallery of Math Art: benice equation

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,676

Hi;

Are exponents allowed? I thought they were not.

Hi Benice;

If they are then nice solution!

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

Offline

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

Awesome! Thanks!!!

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,393

It is a nice solution.

But I thought you weren't allowing powers.

That's why I asked for the exact wording.

So is this question done now?

Bob

Offline

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

Not sure about powers; I must confirm this with the friend who gave me the problem.

Either way, I could not go that close myself!

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,676

Hi anna_gg;

If it does not include powers can you have your friend clearly state what is good and what is not?

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

Offline

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

Confirmed that powers are allowed!

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,676

Hi;

Then I guess this question is closed unless you want more of them.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

Offline

**anna_gg****Member**- Registered: 2012-01-10
- Posts: 113

Thank you all for your help!!

Offline

Pages: **1**