In mathematics, the correct symbol for "directly proportional to" is the Greek letter "a." The concept of proportionality describes the relationship between two numbers or two variables. While the Greek letter "a" does not exist in any of the Wingdings fonts (Wingdings, Wingdings 2 or Wingdings 3), it does exist in another font found on most word processing programs: Symbol.
Turn on your computer.
Open your computer's word processing program.
Open a new document. Some word processors may do this automatically when you open the program.
Click the "Format" tab.
Select "font" from the drop-down menu.
Find the font called "Symbol" from the list of options. Click to highlight it, then select "OK."
Press the "a" button on your keyboard to see the Greek letter "a." Do not type an uppercase "A," as this will result in the wrong symbol.