Old Hollywood: Lewis sensationally revealed in her 1994 memoir that she was conceived in 1935 when Loretta Young, 22, and the married Clark Gable, 34, were shooting The Call of the Wild. Secret: Loretta Young is pictured with Judy Lewis in 1944, who did not know for years who her father was.
The sigma symbol provides the character used to denote the sum of an equation in mathematics. You can create a sigma sign by accessing the Character Palette, using a keyboard shortcut or by using the Special Characters menu in your current application.
Make two columns, one labeled sigma and one labeled pi. Now, look at the Lewis dot structure of a molecule. For every single bond you see, put a tally in the sigma column. For every double bond, put one tally in the sigma column and one in the pi column. For every triple bond, put one tally in the sigma column and two in the pi column.