This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 Precision Precision[ x ] gives the number of digits of precision in the number x. If x is not a number, Precision[ x ] gives the minimum value of Precision for all the numbers that appear in x. Precision gives Infinity when applied to exact numbers, such as integers. Precision gives \$MachinePrecision for machine-precision numbers. See the Mathematica book: Section 3.1.4. See also: Accuracy, N, Chop, SetPrecision, MachineNumberQ. Further Examples Here is an approximate real number. In[1]:= This gives the total number of digits entered to specify the real number. In[2]:= Out[2]= This evaluates using numbers with 30 digits of precision. In[3]:= Out[3]= The result has 30 digits of precision. In[4]:= Out[4]= Mathematica treats 3.0 as a machine-precision number. In[5]:= Out[5]= In[6]:= Out[6]= Giving anything less than \$MachinePrecision digits yields a machine-precision number. In[7]:= Out[7]= This evaluates using 30-digit precision numbers. In[8]:= Out[8]= In this case, the result has a precision of exactly 30 digits. In[9]:= Out[9]= If you give input only to a few digits of precision, Mathematica cannot give you high-precision output. In[10]:= Out[10]= If you want Mathematica to assume that 0.142 is exact, then you have to show this explicitly. In[11]:= Out[11]=