Lenovo PI

While in most keyboards you’ll be having the numeric-keyboard holding ALT and hitting a hex code of 277 following by release of ALT
to render π.

Lenovo keyboards are (naturally) limited by size, first you’ll have to hold Fn (or just click if you’ve previously set the Fn key to be sticky, which I strongly recommend, it is in the BIOS somewhere.. dig it up..) anyway we’re saying..
hold Fn and press the NmLk key (notice its the ScrLk key, with dark-blue’ish sub-print, telling you what function occur when combined with the Fn key).

If you have Lenovo on-screen display you can also see some nice on-screen acknowledge of the NumLock status:

Have a close look on the letters on your keyboard, notice secondary text,
M = 0
J = 1
K = 2
L = 3
U = 4
I = 5
O = 6
(7, 8, 9 will just be the top numeric numbers, but the keyboard API will notice that those are the NUM_KEY 7, 8, and 9, so other HEX value when pressed..!)
and there are the side numeric-keys:
P = *
; = –
(. = still . — but, again, as num_key “.” !)
/ = +

so essentially:

  1. Fn+ScrLk (activate)
  2. Hold Alt and press: K K 7 (release Alt)
  3. Fn+ScrLk (to deactivate)

Usually longer sequence glitch into Unicode, just Google some “ASCII tables” and follow the same method, using the HEX value, to render good-old classic ASCII graphic! :)