One-Number Functions
One-number math functions in the HP-15C operate only upon the number in
the display (X-register).
General Functions
Reciprocal. Pressing ∕ calculates the reciprocal of the number in the
display.
Factorial and Gamma. Pressing ´ ! calculates the factorial of the
displayed value, where x is an integer 0x69.
You can also use ! (x), used in
advanced mathematics and statistics. Pressing ´ ! x + 1),
x). For the Gamma
function, x is not restricted to nonnegative integers.
Square Root. Pressing ¤ calculates the positive square root of the
number in the display.
Squaring. Pressing | x calculates the square of the number in the
display.