IF statements in Excel

Hello,

I'm looking for some help with conditional coding in excel. If text is entered in one of eight specified cells, then I would like 1 added to a "total" cell. It is being used to track total number of patients present at a given time.

For example, if patient names are entered in cells a1, a5 and a9, then a40 would give a value of 3. If no names were entered in the specified cells, a40 would show a value of 0.

Any ideas? I know generally how to use IF and THEN statements, but this is a bit over my head...

Thanks in advance for your help!