How do I use Conditional Formatting to only react to an EXACT MATCH? I tested it on two columns. Column A had numbers 12 to 45. Column B had numbers 120, 121 and 122 - and then I stopped because it forrmatted them all as a "match" because of the "12" and the "21" and the "22" in column A.

Is this beyond the scope of Conditional Formatting? Do I need to try a MATCH function instead?

highlight column A then conditional format / formula is
=ISNUMBER(MATCH(A1,B:B,0))

Thank you so much! That works perfectly for Column A and Column B, but when I tried to edit the formula to expand the comparison range, it didn't work. I tried

=ISNUMBER(MATCH(A1,B:D,0))

I thought that the B:B portion of your original formula was the comparison range - that I would be comparing Column A to Columns B through D - but it didn't work. Is it necessary to create additional conditional formatting rules to compare other columns?

Thank you!

try this --- highlight column A then formula is
=countif($B$1:$D$1000,A1)
and format your colour