What's my number ???

[Gizmonster]

I'm thinking of a number. The number I'm thinking of is either 10, 20, or 30.
You may ask me one question to which I can either reply, "yes", "no", or, "I don't know".
What one question do you ask me so that you can determine what number I'm thinking of ????
Don't bother asking, "what number are you thinking of", or anything like that, 'cos I can only reply, "yes", "no", or, "I don't know".

[bednobs]

£161m - do they realise they could give £2m to everyone in the land and still have £40m left?
wouldn't that be two pound to everyone?

[Safiya]

please.... for the sake of my sanity someone get it!!!! lol

[micmak]

I've been trying to work this out since yesterday :-(

[factor-fiction]

I say to you:

"I have chosen one of those numbers except I can tell you mine is not 30.
Is your number bigger than mine?"

If you had 10 then your answer is no
If you had 20 then your answer is “don’t know”
If you had 30 then you have to say YES

Does that work?

[Frank97]

How would they know you hadn't chosen 10?

[Quassia]

http://www.google.co....,s:0&biw=1093&bih=427

[factor-fiction]

It wouldn't matter D97x7

If you had 10 then your answer has to be no because your 10 can not be greater than my number (10 or 20)
If you had 20 then your answer can only be “don’t know” because you don't know whether I have 10 or 20
If you had 30 then you have to say YES becasue mine is 10 or 20

[grasscarp]

I would ask you - If there's a Y in the number is it twenty. That way if you answer anything at all it would mean there is a y in the number, and if you say yes it is twenty and if you say no it is thirty. If you dont answer me then it is ten.

[Frank97]

OK, my head hurts now :-)

[Frank97]

Now that sounds good grasscarp.

[Psybbo]

I give up!

[Frank97]

Me to!

[micmak]

This has started to get on my nerves. I wish Gizmonster would return and give us the answer?

[factor-fiction]

I like grasscarp's answer which works provided silence is an acceptable option.
I'm also certain mine works though
Where has Gizmonster gone.

Reminds me of the old joke: "how do you keep idiots in suspense?...".

[Gizmonster]

Soz - last time I looked there was only 1 reply.
Silence is not an option though :(
You are close - the question you ask, involves you choosing some number(s) and asking me a question about my choice of number(s) and yours.

[factor-fiction]

Is my last answer not correct then, Gizmonster?
I'll set it out again.


"I have chosen one of those numbers except I can tell you mine is not 30.
Is your number bigger than mine?"


If you had 10 then your answer has to be 'no' because your 10 cannot be greater than my number (which was 10 or 20)
If you had 20 then your answer can only be “don’t know” because you don't know whether I have 10 or 20
If you had 30 then you have to say 'YES' because mine is 10 or 20 .

You could vary mine to use 20 and 30 and 'is yours less than mine'

[Gizmonster]

Actually, factor30's answer works - soz didn't read all the posts properly.

It's very similar to mine:

I would ask, "I have also chosen a number and I can tell you that I've picked either 15 or 25. Is your number greater than mine?"

If you answer, "no" then you must have picked 10.
If you answer, "I don't know" then you must have picked 20.
If you answer, "yes" then you must have picked 30.

Factor30's answer works equally well though - well done :)

[Gizmonster]

I don't understand what you're getting at.
Facor30's answer and mine are the only viable answers on here .... that I've seen anyway !!!