"isnumber" function for numbers

That function is not in Numbers, as you have surmised. I can think of a few ways to create it:

IFERROR(B2*1=B2*1,FALSE)

IF(ISERROR(VALUE(B2)),FALSE,TRUE)

Neither of these is an exact replication of ISNUMBER because they will be TRUE for blank cells while ISNUMBER will be FALSE. Using ISNUMBER on a blank cell in Excel creates a warning, though.

The first one is the closest to ISNUMBER. It and ISNUMBER return TRUE for durations as well as numbers. The second one returns FALSE for durations.

So, to replicate your function I think it would be:

=IF(IFERROR($B$3*$C$3=$B$3*$C$3,FALSE),INDEX($A$1:$B$11,MATCH($B$3,$A$1:$A$11,2) *$C$3,""))

CAUTION

If you apply your tests will flag blank cells as numbers values.

=VALUE(blank cell) returns 0

=blank cell1 *blank cell2 returns 0

What is the tue ISNUMBER function returning when it is applied to a blank cell ?

Yvan KOENIG (VALLAURIS, France) dimanche 11 avril 2010 08:14:40

In Excel WIKI, I found that ISNUMBER returns false if the tested cell is blank.

So, I would use this formula:

=IF(IF(OR(ISBLANK($B$3),ISBLANK($C$3)),FALSE,IF(ISERROR($B$3*$C$3),FALSE,TRUE))= TRUE,INDEX($A$1:$B$11,MATCH($B$3,$A$1:$A$11),2)*$C$3,"")



CAUTION :

There was a typo in your original one and in the Badunit one.
A parenthesis was missing just before ,2)
and so they were an extraneous one at end.

Yvan KOENIG (VALLAURIS, France) dimanche 11 avril 2010 11:57:12

It does appear that for the example formula it might be necessary to return FALSE for blank cells. I did mention that the formulas I provided for ISNUMBER would return TRUE for blank cells, contrary to how ISNUMBER works, just in case it was a problem.