Conditional Formatting keeps wanting me to type apostrophes

IF(logical_test, value_if_true, [value_if_false])

logical_test (required) - The condition you want to test.
value_if_true (required) - The value that you want returned if the result of logical_test is TRUE.
value_if_false (optional) - The value that you want returned if the result of logical_test is FALSE.

your logical_test is : ISNUMBER(06) = always TRUE
but you forgot about value_if_true and value_if_false so function IF() doesn't know what to show.

edit:
but if you want to check number or not number enough to use =ISNUMBER(A1) (cell address change suitable). Result will be TRUE/FALSE so it will enough for CF

Conditional Formatting works only on TRUE or FALSE, so you only need to structure your formulas to return that...
=IF(ISNUMBER(06))
just needs to be...
=ISNUMBER(06)
Sandy's suggestion should work for you

Originally Posted by FDibbins

Conditional Formatting works only on TRUE or FALSE

It will also work with formulas that return numbers.

Any number other than 0 will evaluate as TRUE. 0 will evaluate as FALSE.

Thanks for that Tony, good to know

You can use all three conditions: =AND(ISNUMBER(A1),A1>0) . why three? because A1<>"" is included in A1>0

so if:
A1 = xyz (text) result = FALSE
A1 = 0 or -123 result = FALSE
A1 > 0 result = TRUE
check logical of AND function

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