• NumberFormat is an option for NumberForm and related functions which specifies how the mantissa, base and exponent should be assembled into a final print form.
• With the setting NumberFormat -> f, the function f is supplied with three arguments: the mantissa, base and exponent of each number to be printed.
• The arguments are all given as strings.
• When no exponent is to be printed, the third argument is given as "".
• The function f must return the final format for the number.
• New in Version 2.