One of the applications in Google Drive. The Spreadsheets application allows users with a Google account to create and edit worksheets and workbooks online.
Within the worksheet, all basic functions (see complete list) and more are present to accomplish many goals. If extra measures are needed, Google Apps Script (GAS home page) can create custom functions and allows for extra flexibility inside and outside the workbook.
(* to indicate that you want to convert the spreadsheet to PDF in Google Drive)