Emma,

I understand that if the assignment asks you to use IF(),
you "must" use IF(), even though MAX() seems to be the
better choice. You might want to ask your instructor
(if you have one) what they are looking for and why.

Michael wrote:
However, knowing some tutors, they throw in a question
to see if you can think around it. Try this
=IF(A1:A19="","",MAX(A1:A19))

Dovetailing what Michael said, perhaps the following is
something like what the assignment is looking for:

=IF(NOT(ISNUMBER(A1:A19)),"",MAX(A1:A19))

The point is: create a formula that will display the
max without ever incurring an error. It's called
"bullet-proofing", and it is certainly a useful ability
for a professional to learn.