This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 Cancel Cancel[ expr ] cancels out common factors in the numerator and denominator of expr. Example: Cancel[(x^2-1)/(x-1)]. Cancel is Listable. Cancel cancels out the greatest common divisor of the numerator and denominator. Cancel[ expr , Modulus-> p ] generates a result modulo p. Cancel[ expr , Extension->Automatic] allows operations to be performed on algebraic numbers in expr. Cancel[ expr , Trig -> True] treats trigonometric functions as rational functions of exponentials, and manipulates them accordingly. See the Mathematica book: Section 1.4.5, Section 3.3.3. See also: Apart, GCD. Further Examples This cancels common factors in each fraction. In[1]:= Out[1]= This uses multiple-angle formulas. In[2]:= Out[2]= This cancels over the integers modulo . In[3]:= Out[3]= To cancel out common factors in the numerator and denominator, you can set Extension -> Automatic. In[4]:= Out[4]= In[5]:= Out[5]=