Parentheses are very important in spreadsheets because like all programming, spreadsheet formulas have to be very specific. A big formula, especially one like Viete’s approximation of pi, likely will require us to think both in parentheses and in creating formulas that naturally build a series. This one is quite interesting and you will know if you are approaching the right answer if you are approaching the value of pi. So be careful and watch your (parentheses).