On Tue, 15 Dec 2009 11:14:01 -0800, Mike H
wrote:

I just checked E2003 and you are correct but there is no such explanation of
this limitation in E2007 help reproduced below

That's funny. With Excel 2007, when I look at HELP for BIN2DEC, I see:

Number is the binary number you want to convert. Number cannot contain more
than 10 characters (10 bits). The most significant bit of number is the sign
bit. The remaining 9 bits are magnitude bits. Negative numbers are represented
using two's-complement notation.

Seems pretty clear to me.
--ron