A standard feature of
PC keyboards, consisting
of a rectangular array of 17 extra keys at the right-hand end:
0-9, .,
Num Lock, /, *, -, + and
Enter. Apart
from Num Lock, these typically duplicate the function of other
keys but are designed to make entering basic numerical
calculations as quick as on a digital calculator. It is
often possible to assign completely different functions to
these keys according to the needs of a particular application.