SiliconGlen, Scotland. Tartan Tech Talk.

It's chip and PIN. Not "chip and PIN Number". A PIN IS a number, since PIN stands for Personal Identification Number.

Asking me for my PIN Number is the same as asking me for my Personal Identification Number Number, which is of course ridiculous.

Now, repeat together after me:

Please enter your PIN, NOT Please enter your PIN Number.
Please enter your PIN, NOT Please enter your PIN Number.
Please enter your PIN, NOT Please enter your PIN Number.
Please enter your PIN, NOT Please enter your PIN Number.
(that's once for every digit).