Functions 101

A function is a named shortcut: =SUM(B2:B6) instead of =B2+B3+B4+B5+B6.

The pattern is always the same: name, open parenthesis, inputs separated by commas, close parenthesis. B2:B6 is a range, meaning every cell from B2 through B6.

The ones you'll use constantly: SUM, AVERAGE, ROUND, COUNT, COUNTA, and the Sheets-only COUNTUNIQUE.