URTH 

From: "Andy Robertson"Subject: Re: (urth) Base 9 on the Whorl? Date: Sun, 12 May 2002 09:05:39 +0100  Original Message  From: "Robert Borski" > Yes. But if indeed the children are making mistakes, they are making the > less likely one. 29  19 in base 10 is almost impossible to get wrong It is 10 in any base whatever. > our solution. But a calculation in base 9 of 7 + 17 is much more difficult, > even for adults; you need to figure out (or memorize by rote) that the > number 17 only contains 16 integers No, no,no. All you need to know is that 7+7 = 15. You put 5 down and carry 1 making 25. It's a fascinating idea, Robert, but there is no evidence for it. hartshorn (I did teach my kids base 9  as a mental exercise for them) 