In a list, between commas, or following a comma, a normal ellipsis is used, as in:

  
    
      
        1
        ,
        2
        ,
        3
        ,
        …
        ,
        100
      
    
    {\displaystyle 1,2,3,\ldots ,100}
  or to mean an infinite list, as:

  
    
      
        1
        ,
        2
        ,
        3
        ,
        …
      
    
    {\displaystyle 1,2,3,\ldots }
  To indicate the omission of values in a repeated operation, an ellipsis raised to the center of the line is used between two operation symbols or following the last operation symbol, as in:

  
    
      
        1
        +
        2
        +
        3
        +
        ⋯
        +
        100
      
    
    {\displaystyle 1+2+3+\cdots +100}
  Sometimes, e.g.
(see factorial)Normally dots should be used only where the pattern to be followed is clear, the exception being to show the indefinite continuation of an irrational number such as:

  
    
      
        π
        =
        3.14159265
        …
      
    
    {\displaystyle \pi =3.14159265\ldots }
  Sometimes, it is useful to display a formula compactly, for example:

  
    
      
        1
        +
        4
        +
        9
        +
        ⋯
        +
        
          n
          
            2
          
        
        +
        ⋯
        +
        400
      
    
    {\displaystyle 1+4+9+\cdots +n^{2}+\cdots +400}
  Another example is the set of positive zeros of the cosine function:

  
    
      
        
          {
          
            
              
                π
                2
              
            
            ,
            
              
                
                  3
                  π
                
                2
              
            
            ,
            
              
                
                  5
                  π
                
                2
              
            
            ,
            …
          
          }
        
      
    
    {\displaystyle \left\{{\frac {\pi }{2}},{\frac {3\pi }{2}},{\frac {5\pi }{2}},\ldots \right\}}
  There are many related uses of the ellipsis in set notation.