Everyone should be aware of the essential spreadsheet formulas.

Vlookup and hlookup are recommended by the recommendations already made.But I would also add =today, =day also month and year if your looking to run analysis on things like service standards/time elapsed etc and if you are working with data which you didn't produce the following can be very helpful for getting the data into a useable format: =proper, =trim, =len, =left, =right and =concatenateI'm happy to tell you more about these.