Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.
function toPrecision ( [precision : Number] ) : String
Optional. Number of significant digits. Must be in the range 1 вЂ“ 21, inclusive.
For numbers in exponential notation, precision - 1 digits are returned after the decimal point. For numbers in fixed notation, precision significant digits are returned.
If precision is not supplied or is undefined, the toString method is called instead.