validation formula's and conditional formatting

[VanessaS]

I have created a drop down menu using 'data' - 'validation'. the options are
'1', '2', and '3'. there are a total of six cells that these numbers can can
be entered into.

My questions are:
A) i want to limit people from entering '1' maximum once, '2' max. three
times, and '3' max. two times.
B) i want an 'error' or 'alert' to occur if these max. limits of 1 once, 2
three times, and 3 two times is entered.

Is it possible to do both of the options above?

 

[Bob Phillips]

Just enter a normal DV in cell A1 with a list of 1,2,3. But in A2:A6, use
custom with a formula of

=OR(AND(A2=1,COUNTIF($A$1:$A2,A2)=1),AND(A2=2,COUNTIF($A$1:$A2,A2)<=3),AND(A2=3,COUNTIF($A$1:$A2,A2)<=2))