Section 6: Functions 80
Y-register, the y value is divided by x and the remainder is placed back into the X-register. For example, find 128 modulo 10:
Keystrokes Display
128 ENTER
 128
The y-value.
10
 10 _
The x-value.
XEQ
 XEQ _ _

ALPHA MOD ALPHA
 8
The value is in X.
Performing y mod x when x=0 returns an answer of 0.
Reciprocals
To calculate the reciprocal of a number in the X-register, key in the number, then execute the 1/x (reciprocal) function. For example, to calculate the reciprocal of the number 1.7588028 × 1011 (the electron charge-to-mass ratio):
Keystrokes Display
1.7588028 EEX 11
 1.7588 – 11
The number.
1/x
 5.6857 – 12
The reciprocal.
You can also calculate the reciprocal of a value in a previous calculation without reentering the number.
Example: In an electric circuit, three resistors are connected in parallel and a single resistor is connected in series with the parallel circuit. The resistors in parallel have values of 2.7 kilohms, 5.6 kilohms, and 7.5 kilohms, and the series resistor has a value of 680 ohms. What is the total resistance of the circuit?
1       1
Rt = + R4 = +  680

1 + 1 + 1
R1 R2 R3

1 + 1 + 1
2700 5600 7500

Keystrokes Display
2700 1/x
 0.0004

5600 1/x
 0.0002

+
 0.0005

7500 1/x
 0.0001

+
 0.0007
Sum of the reciprocals.
1/x
 1,465.6844
The reciprocal of the sum of the reciprocals.
680  +
 2,145.6844