**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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