Welcome to BrainDen.com - Brain Teasers Forum
|Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.
Of course, you can also enjoy our collection of amazing optical illusions and cool math games.
If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.
Thanks and enjoy the Den :-)
Posted 04 December 2007 - 01:06 AM
2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9
Posted 17 December 2007 - 02:46 AM
The only possible numbers A could have and be certain of B's number are 2, 3, 8, and 9.
If A had any of 4, 5, 6, or 7, then he would not be certain of B's number.
Posted 17 December 2007 - 09:29 PM
Posted 20 December 2007 - 09:19 PM
Posted 18 February 2008 - 08:22 AM
Easy Savoury - Back to the Number Puzzles
A teacher thinks of two consecutive numbers between 1 and 10 (Edit: 1 and 10 included). The first student knows one number and the second student knows the second number. The conversation of the students is as follows:
First: I do not know your number.
Second: Neither do I know your number.
First: Now I know.
Will you find all 4 solutions?
First: 3 Second: 4
First: 2 Second: 3
First: 8 Second: 7
First: 9 Second: 8
Posted 30 October 2008 - 08:10 PM
Since the first child does not know the other's number, he does not have a 1 or a 10. (Or he would know the other student's number would be 2 or 9 respectively.
Now the second child knows that the first child does not have a 1 or a 10, he knows that if he has a 2 or a 9 then the other child must have a 3 or an 8, respectively. He says he does not know, so therefore he does not have a 1, 2, 9 or 10.
The first child now knows that the second child does not have a 1, 2, 9 or 10, and we know that the first doesn't have 1 or 10. The only way the first child would know the answer at this point is if he has a 2, a 3, an 8 or a 9.
If child 1 has a 2: Child 2 does not have 1(discovered earlier) or 2(I have it), the only other consecutive number is 3.
If child 1 has a 3: Child 2 does not have a 2(discovered earlier) or a 3(I have it), the only other consecutive number is 4.
If child 1 has an 8: Child 2 does not have a 9(discovered earlier) or an 8(I have it), the only other consecutive number is 7.
If child 1 has a 9: Child 2 does not have a 10(discovered earlier) or a 9(I have it), the only other consecutive number is 8.
Therefore the only possible answers are:
2 and 3
3 and 4
7 and 8
8 and 9
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users