S soroban Elite Member Joined Jan 28, 2005 Messages 5,584 Dec 1, 2008 #1 We can arrange nine coins and make eight rows of three coins each. Code: o - o - o | \ | / | o - o - o | / | \ | o - o - o Now arrange the nine coins and make ten rows of three coins each.
We can arrange nine coins and make eight rows of three coins each. Code: o - o - o | \ | / | o - o - o | / | \ | o - o - o Now arrange the nine coins and make ten rows of three coins each.
S soroban Elite Member Joined Jan 28, 2005 Messages 5,584 Dec 2, 2008 #2 I called it an "oldie" because I saw this one many many years ago. And I was sure that someone had seen it . . . or that someone could solve it. The solution is disarmingly simple . . . *In the middle row, note that coins on the ends. Move both of them a half-unit inward. Now count the rows-of-3.*
I called it an "oldie" because I saw this one many many years ago. And I was sure that someone had seen it . . . or that someone could solve it. The solution is disarmingly simple . . . *In the middle row, note that coins on the ends. Move both of them a half-unit inward. Now count the rows-of-3.*
