In either Excel 2000 or 2003, BIN2HEX(511) returns #NUM!, as it should (since
511 is not binary as other replies have noted).

If you meant that =BIN2HEX(DEC2BIN(511)) returns '1FF', but
=BIN2HEX(DEC2BIN(512)) returns #NUM!; that is because =DEC2BIN(512) also
returns #NUM!, as documented in Help.

Jerry

"pellis" wrote:

BIN2HEX is acting really wierd. BIN2HEX(511) works fine. BIN2HEX(512)
returns a #NUM! error.

Also, can't figure out how to input a hex number into the worksheet. If I
input '43E2', the worksheet will NOT recognize this as a hex number. Is
there some type of indicator I need to use? Could not find ANYTHING in the
help sections.