You can do this using data validation.

Select the cell in question. Assume this is for cell A1.
Goto the menu DataValidation
Allow: Custom
Formula: =AND(A11,MOD(A1,2)=0)

Select the Error Alert tab. There you can enter a message that pops up if a
user enters an invalid entry.

The above formula will only allow entries that are numbers and multiples of
2.

--
Biff
Microsoft Excel MVP


"Yvonne" wrote in message
...
Hi,

I need some assistance in a order form which i am currently doing up.
There
is a section on the order where you can enter the quantity and the
quantity
must be in lots of twos. I was just wondering if there is any way, when
you
enter a quantity and if the quantity is not in lots of two a message can
pop
up saying "Please enter in multiples of 2 units" or if the value they
enter
in is not numerical a message can pop up saying something like "Please
enter
a numerical value". If someone can point me into the right direction it
would
be much appreciated. Looking forward to hear from you soon!

Kind Regards
Yvonne