When performing an equation that deals with a percentage, say figuring local sales tax into a grocery list, Calc mis-handles the equation. For example, if C14 has a total of 449.98, cell A18 has the tax rate of 10.10%, and cell D14 has the equation "=C14*B18" the total amount of tax owed is displayed. If you then try to add the values of D14 and C14 using the equation "=C14+D14" the cell displays "49542.80%". I copied this exact spreadsheet into my wifes copy of Microsoft Office 365 Student Excel and it displayed the proper value of D14+C14 in the cell.