What is Calc?
Calc is the spreadsheet component of OpenOffice.org (OOo). You can enter data, usually numerical data, in a spreadsheet and then manipulate this data to produce certain results.
Alternatively you can enter data and then use Calc in a ‘What If...’ manner by changing some of the data and observing the results without having to retype the entire spreadsheet or sheet.
A major advantage of electronic spreadsheets is that the data is easier to alter. If the correct functions and formulas have been used, the program will apply these changes automatically.