Wolfram Research, Inc.
Input forms for numbers.
Numbers can be entered with the notation base^^digits in any base from 2 to 36. The base itself is given in decimal. For bases larger than 10, additional digits are chosen from the letters a-z or A-Z. Upper- and lower-case letters are equivalent for these purposes. Floating-point numbers can be specified by including . in the digits sequence.
In scientific notation, mantissa can contain ` marks. The exponent n must always be an integer, specified in decimal.
The precision or accuracy p can be any real number; it does not need to be an integer.
In the form base^^number`p the precision p is given in decimal, but it gives the number of digits of precision in the specified base, not in base 10.