HP 15c - Manual (Page 16)

16 The HP-15C: A Problem Solver
With this program loaded, you can quickly calculate the time of descent of
an object from different heights. Simply key in the height and press
´A. Find the time of descent for objects released from heights of
100 m, 2 m, 275 m, and 2,000 m.
The answers are: 4.5175 s; 0.6389 s; 7.4915 s; and 20.2031 s.
That program was relatively easy. You will see many more aspects and
details of programming in part II. For now, turn the page to take an in-depth
look at some of the calculator's important operating basics.