typing pie from keyboard in vi

[Tapas Mishra]

Is there a way I can type the mathematical symbol pie from my keyboard.
Recently one of the professional  networking website where I was logging in
asked me to enter CAPTCHA and in their security verification  image
they had given pie to be entered.
I do not use Windows to use any type of virtual keyboard.
Where in my US English keyboard I can do that.

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Tapas