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 :-)
Guest Message by DevFuse

Penny's triple play

Best Answer CaptainEd, 15 February 2013 - 04:56 PM

Spoiler for with all pennies flat on the table

Go to the full post

11 replies to this topic

#1 bonanova

bonanova

bonanova

• Moderator
• 6160 posts
• Gender:Male
• Location:New York

Posted 15 February 2013 - 07:12 AM

I put a handful of pennies on the table and I wondered whether I could group them so that each penny touched three and only three of the others. It took a while but I found it was possible. I then wondered whether I could do it with fewer pennies. It was clear that I could not.

How many pennies were in the group?

• 0

Vidi vici veni.

#2 witzar

witzar

• Members
• 233 posts

Posted 15 February 2013 - 02:50 PM

Is it required for each coin to touch fully table surface with one of its faces?

• 0

#3 CaptainEd

CaptainEd

Senior Member

• Members
• 1094 posts

Posted 15 February 2013 - 04:56 PM   Best Answer

Spoiler for with all pennies flat on the table

• 0

#4 Prime

Prime

Senior Member

• Members
• 872 posts
• Gender:Male
• Location:Illinois, US

Posted 15 February 2013 - 05:02 PM

Spoiler for the fewest

• 0

Past prime, actually.

#5 CaptainEd

CaptainEd

Senior Member

• Members
• 1094 posts

Posted 15 February 2013 - 05:14 PM

good solve, prime!

• 0

#6 witzar

witzar

• Members
• 233 posts

Posted 15 February 2013 - 05:22 PM

Can you prove, that required arrangement is not possible with odd number of coins?

• 0

#7 bonanova

bonanova

bonanova

• Moderator
• 6160 posts
• Gender:Male
• Location:New York

Posted 15 February 2013 - 07:57 PM

Spoiler for Sure

• 0

Vidi vici veni.

#8 bonanova

bonanova

bonanova

• Moderator
• 6160 posts
• Gender:Male
• Location:New York

Posted 15 February 2013 - 08:02 PM

Spoiler for the fewest

Outside the box; off the table.
Honorable Mention for sure.
• 0

Vidi vici veni.

#9 Prime

Prime

Senior Member

• Members
• 872 posts
• Gender:Male
• Location:Illinois, US

Posted 15 February 2013 - 08:41 PM

Spoiler for Sure

Completely off the topic, a technical issue. I cannot see the contents of the spoiler in the post. It appears as empty line. When I "quote" the post, the spoiler becomes visible inside the "quote".

• 0

Past prime, actually.

#10 bonanova

bonanova

bonanova

• Moderator
• 6160 posts
• Gender:Male
• Location:New York

Posted 15 February 2013 - 11:28 PM

There do seem some irregularities with the site. I can see the contents.

You might send a PM to Rookie1ja with your specifics.

I would have, instead of this post, but I don't know how simultaneously to PM to two people.

• 0

Vidi vici veni.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users