You can use data validation.

Select the cell where you want to restrict input, A1 in my example. From
the menus DataValidation. Select Custom in the Allow dropdown. In the
formula box enter "=MOD(A1,66)=0" (without quotes - change cell
reference to match selected cell).

On the Error Alert tab you can set your own error message eg must be
multiple of 66.

Hope this helps
Rowan

Eintsein_mc2 wrote:
I have a worksheet that is a quote form for quoting on bricks. Bricks
are only avaliable in lots of 66. So if my sales people are giving a
quote say for 3000 bricks this would not be possiable because they only
come in lots of 66, the figue they would have to enter would be 3036. I
was wondering if there is a way to get the cell to show an error if the
figue entered dose not work with multiables of 66. Thanks