Section 2: Numeric Functions  29 
Two-Number Functions 
The  HP  15c  performs  two-number  math  functions  using  two  values 
entered sequentially into the display. If you are keying in both numbers, 
remember  that  they  must  be  separated  by  v  or  any  other 
function—like | ‘ or ⁄—that terminates digit entry. 
For a two-number function, the first value entered is considered the y-
value  because it  is  placed into  the  Y-register  for memory  storage.  The 
second value entered is considered the x-value because it remains in the 
display, which is the X-register. 
The arithmetic operators, +, -, *, and ÷, are the four basic two-
number functions. Others are given below. 
The Power Function 
Pressing y calculates the value of y raised to the x power. The base 
number, y, is keyed in before the exponent, x. 
 
To Calculate
Keystrokes  Display 
2
1.4
 
2 v 1.4 y 
 2.6390 
2
−1.4
 
2 v 1.4 ” y 
 0.3789 
(−2)
3
 
2 ” v 3 y 
-8.0000 
2
3
 or 2
⅓
 
2 v 3 ⁄ y 
 1.2599 
Percentages 
The percentage functions, k and ∆, preserve the value of the original 
base  number  along  with  the  result  of  the  percentage  calculation.  As 
shown  in  the  example  below,  this  allows  you  to  carry  out  subsequent 
calculations using the base number and the result without re-entering the 
base number. 
Percent. The k function calculates the specified percentage of a base 
number.