Retro Review: Texas Instruments Explorer Plus

Retro Review:  Texas Instruments Explorer Plus

General Information

Company:  Texas Instruments
Type:  Scientific - Algebraic
Display:  10 digits or 5 digits with 2 digit exponents
Power:  Solar
Memory:  1
Years:  1995 - 1997 (two editions).  I have a the 2nd edition.
Original Cost: $24.95
Documentation:  Manual
Datamath page:  http://www.datamath.org/Sci/Modern/TI-32EXPLUS_2.htm

Features
* Trigonometry, Logarithms
* Degree and Radian mode
* 1 Variable Statistics
* Backspace key
* Fractions with simplification
* 2 Stored Operations (Macros)
* Random Numbers
* Factorial, Combinations (nCr), Permutations (nPr)

Fractions

The Explorer Plus dedicates six keys to fractions. 

[Unit]:  Enter the unit portion of a mixed fraction.  A small "u" separates the whole unit and its fraction.

[ / ]:  Use this to separate a fraction's numerator and denominator.  This is not the same as the division key [ ÷ ].

[ F <> D]:  Change a result from fraction to decimal and vice versa.  Changing to a fraction is does not always change the decimal to the fraction

[ Simp ]:  Use this key to simplify fractions.  I'll talk about this in a bit.

[ A b/c ]:  Change an improper fraction to a mixed fraction.

[ x<> y ]:  Exchange entries.  This works for operations outside the fraction commands. 


Changing to a mixed fraction with the [ A b/c ] key

Example:  Change the improper fraction 74/11 to a mixed fraction.

Keystrokes:  74 [ / ] 11 [ A b/c ]

Result:  6 u 8/11

Simplifying a Fraction

If a result has the display "N/D → n/d" on the left side, this means the fraction can be simplified.  Fractions can be fully simplified, or you can provide a factor. 

Example:  Fully simplify 88/55.

Keystrokes: 88 [ / ]  55 [ = ] [Simp] [ = ]

Result: 8 / 5

Press [ x<>y ] to get the factor used to reduce the fraction, in this case, it would be 11.

Example:  Reduce the fraction 284/404 by a factor of 2.

Keystrokes:  284 [ / ] 404 [ = ] [Simp] 2 [ = ]

Result:  142 / 202

π and Fractions

In Radians Mode, you can work with fractions involving π.  The display will show "Pi". 

Example:  π/4 + 3π/6

Keystrokes:  [ 2nd ] [ π ] (DR>) until RAD shows in the display

[ π ] [ / ] 4        Display:  Pi/4
[ + ] 3 [ π ] [ / ] 6      Display:  3Pi/6
[ = ]     Display:  9Pi/12

Result: 9π/12

For the decimal answer, press [ F<>D ] to get 2.35619449.

Other Keys of Interest

Integer Division

The integer division [ INT÷ ] will display the quotient and remainder of the division problems of two integers.  The displays the quotient by Q and remainder by R.  If you use the result in future calculations, only the integer portion is carried over. 

Example:  Use the integer division command on 128 ÷ 35

Keystrokes:  128 [ INT÷ ] 35 [ = ]

Result:  Q:  3,  R:  23


Random Numbers

The RAND command on the Explorer Plus has two functions:

RAND by itself:  a three digit number between 0.000 and 0.999.  Press [ 2nd ] [ = ] (RAND)

Integer Random Number:  You can get a random integer from 1 to n (up to 100) by the this keystroke sequence:  1 [ 2nd ] [ = ] (RAND) n [ = ].

Example:  Generate a random integer from 1 to 50.

Keystrokes:  1 [ 2nd ] [ = ]  (RAND) 50 [ = ]

Results may vary.


 Stored Operations

You can store simple operations in one of two OP registers, OP1 and OP2.  The operations that can be included are +, -, *, ÷, y^x, INT÷, y^(1/x), nCr, nPr, and random numbers.

Example:  Store x + 6 in OP1. 

[CE/C] (or suitable number) [ + ] 6 [ OP1 ]

11 + 6, 15 + 6, 28 + 6

11 [ OP1 ]  Display:  1        17
15 [ OP1 ]  Display:  1       21
28  [ OP1 ] Display:  1      34

You can repeat operations. 

Clear stored operations by either pressing [ON/AC], which will clear everything, or pressing [2nd] (

Verdict

I really like the the Explorer Plus and I think it would have a made a great base for the current TI-30X generation.  Texas Instruments could have used the TI-40 College (France), which added the rectangular/polar and degrees/degrees-minute-seconds conversion, along with the DIV command (don't know what that does). 

This is a solid calculator for a basic scientific calculator.  I like the emphasis on fractions and it contains the basic scientific calculator functions. 

Eddie

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TI-34 II, TI-34 Multiview, TI-36X Pro: Stored Operations and Recurring Sequences

TI-34 II, TI-34 Multiview, TI-36X Pro: Stored Operations and Recurring Sequences 

Although not known as programming calculators, we can program small macros on the Texas Instruments TI-34 II, TI-34 Multiview, and TI-36X Pro calculators through the stored operation feature. You can store up to two operations on the TI-34 II and TI-34 Multiview, while only one operation can be stored on the TI-36X Pro.   The elementary calculator TI-15 also has this feature.  

Executing the stored operation types whatever is stored.  For example if op=+11, then pressing 12 [op]* shows 12+11 on the screen.  

There are limits to what can be programmed with this operation:

1.  For functions f(X), X is assumed to be entered, as once the operation is executed, what is stored is typed out. 

2. There are no loops or IF-THEN-ELSE structures, hence the extent of the the stored operation is meant for quick calculations. I believe there is a 40 character limit. 

3. For certain operations, you may need to enter certain functions or left hand parenthesis before executing the operation.  

4. With the last answer command (Ans), we can program recurring sequences with one initial condition.  We will discuss this later. 

General Steps for the TI-34 II and TI-34 Multiview:

1.  Press [2nd] [OP1] (set op1, >OP1) to edit your macro.  Press [Clear] if necessary.  

2. When done, press [ENTER]

3. Enter your variable, press [OP1].  The calculation is automatically made. 

The steps are similar for OP2. 

General steps for the TI-36X Pro (TI-30X Pro Multiview if you are outside the United States):

1.  Press [2nd] [ * ] (set op) to edit your macro.  Press [Clear] if necessary.  

2. When done, press [ENTER]

3. Enter your variable, press [2nd] [ ) ] (op). The calculation is automatically made.  

For the TI-15, the [OP1]/[OP2] has required repeated presses.  First for the edit mode, second to store the operation, subsequent presses execute the operation.  The TI-15 may have limited application, as in one step arithmetic macros.  I don't know if more complex macros can be programmed for the TI-15, since I do not own one.  For this post, I will focus on the TI-34 II, TI-34 Multiview, and TI-36X Pro.

Let's go over a few examples. 

Example 1: Area of a circle.   

The area of the circle is A = π * r^2.  Assume r will be in the display.  

Set up the operation.  Press [2nd], (set op 1/2)*, [x^2], [ * ], [ π ].  The screen will read: 

op=²*π, op1=²*π, or op2=²*π

Don't freak at this display, it is correct.  Press [ENTER].  Remember, this will be attached to the calculation whenever the stored operation is executed. 

*Refer to the instructions above for your particular calculator. 

Now enter r, and then press {op} to calculate the area.  

Test Data:

r = 0.76,  Result = 1.814583917

0.76 {op} (display should show 0.76² * π )

r = 9, Result = 81*π = 254.4690049

Example 2: Convert °C to °F. (Degrees Celsius to Fahrenheit) 

Formula: °F = °C * 9/5 + 32

Stored operation:  op = * 9 ÷ 5 + 32

Execute this stored operation in the same way as the above example.  

Test data:

32°C, result 89.6°F

24°C, result 75.2°F

Example 3: Hypotenuse of a Right Triangle

Calculate the hypotenuse of a right triangle where one side is 5 units and the other varies.  Formula:  √(x^2 + 5^2) = (x^2 + 5^2)^0.5

Here X is inside an operation, so we'll need to make some adjustments.  Store the operation as:

op = ² + 5² ) ^ 0.5

When executing the operation, we'll have to include the left parenthesis, then enter the number, then execute the operation ({op}).  Otherwise, a syntax error occurs. 

Test data:

x = 3.   Press [ ( ], 3, {op}.   The display should read (3² + 5²)^0.5 for the result of 5.830951895.  

x = 4.5. Result: 6.726812024. 

Example 4:  Percent Change

This will illustrate the use of variable registers.  The TI-34 II has five variable registers (A-E), the TI-34 Multiview has seven (x,y,z,t,a,b,c), and the TI-36X Pro has eight (x,y,z,t,a,b,c,d).  

For this example, I will use the variable x, but feel free to use which one you like. 

Percent change:  (n - x)/x * 100

where n = new value, x = old value.  

The stored operation will be:  op = - x) ÷ x * 100

To execute, store the old value in x, then press [ ( ], enter new value, then execute the operation.  

Test Data:

New = 50, Old = 36

36 [STO>] x, [ ( ], 50, {op}.   Result: 38.88888889

New = 26, Old = 36. Result: -27.77777778

Recurring Sequences:  u(n) = f( u(n-1) )

The stored operation format will be slightly different.  The variable Ans (last answer) represents u(n-1).  We have more freedom with the expression since Ans is used. 

Before execution the operation, enter the initial condition, press [ENTER] to store in Ans.  Press {op} and repeat as desired.  

Example 5:

Recurring sequence:  u(n) = 3 * u(n-1) - 1 with the initial condition u(1) = 1. 

Stored Operation:  op = 3 * Ans - 1

Find the next six terms.  

1, [ENTER], {op}

The next six terms are 2, 5, 14, 41, 122, 365. 

Hope you find the stored operation feature helpful.  Until next time,

Eddie

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