Find if there is a matching number in another column

[Xhawk57]

is there a way to take two sets of data and mark a third column when the
number from the fist column has a match anywhere in the set (range) of data
for the other column?

for instance i have 3 columns

A B C
1 9
3
9
4

is there a formula that would return a marker in column C by asking the
question "if B1 = any number in column A return an "X""?

 

[Mike H]

Maaybe

=IF(COUNTIF($A$1:$A$50,B1)>0,"X","")

Drag down as required

Mike