### 11.4.8 Converting a real number into a string: format

The format command takes two arguments, a real number and a string used for formatting.
format returns the real number as a string with the requested formatting.

The formatting string can be one of the following:

- f (for floating format) followed by the number of digits to put after the decimal point.
  Input:
  format(sqrt(2)*10^10,"f13")
  Output:
  "14142135623.7308959960938"
- s (for scientific format) followed by the number of significant digits.
  Input:
  format(sqrt(2)*10^10,"s13")
  Output:
  "14142135623.73"
- e (for engineering format) followed by the number of digits to put after the decimal point, with one digit before the decimal points.
  Input:
  format(sqrt(2)*10^10,"e13")
  Output:
  "1.4142135623731e+10"