How to hide individual cells

I have a spread sheet which calculate hours worked, rate of pay and pay earned on a certain date. I have copied the formulas down the column for several weeks. How do I hide the value of the formulas in cells where there is no data input for that row?

Take a look at IF() function: LibreOffice Help - IF

I’d rather recommend conditional formatting (even with IF() calculated) because such hiding IF() clauses in cell calculations usually use "" empty string results to “hide” that then can’t be calculated with in numeric context.