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Section 2: Numeric Functions
For example, to find the sales tax at 3% and total cost of a $15.76 item:
Keystrokes
15.76 v
3 |k
+
Percent Difference. The ∆ function calculates the percent difference
between two numbers. The result expresses the relative increase (a positive
result) or decrease (a negative result) of the second number entered
compared to the first number entered.
For example, suppose the $15.76 item only cost $14.12 last year. What is
the percent difference in last year's price relative to this year's?
Keystrokes
15.76 v
14.12 |∆
Polar and Rectangular Coordinate Conversions
The : and ; functions are provided in the
HP-15C for conversions between polar
coordinates and rectangular coordinates. The
angle θ is assumed to be in the mode, whether
degrees (in a decimal format, not a minutes-
seconds format), radians, or grads. θ is
measured as shown in the illustration at right.
Polar
Conversion.
(polar) converts a set of rectangular coordinates (x, y) to polar coordinates
(magnitude r, angle θ). The y-value must be entered first, the x-value
second. Upon executing |: r will appear in the display. Press ®
(X exchange Y) to bring θ out of the Y-register and into the display (X-
register). θ will be returned as a value between -180° and 180°, between -π
and π radians, or between -200 and 200 grads.
Display
15.7600
0.4728
16.2328
Display
15.7600
-10.4061
Pressing
Enters the base number (the price).
Calculates 3% of $15.76 (the tax).
Total cost of item ($15.76 + $0.47).
This year's price (our base number)
Last year's price was 10.41% less
than this year's price.
|:
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