** Retro Review: Casio fx-55 Fraction Mate**

**Quick Facts**

Model: fx-55 Fraction Mate

Company: Casio

Years: probably the 1990s or early 2000s, predecessor to the fx-55 Plus*

Memory Register: 1 independent memory

Battery: Solar with battery back up (LR44)

Screen: 8 digits, 4 digit numerator, 4 digit denominator, function indicator (+, -, ×, ÷, ^), equals and parenthesis indicators

Logic: Algebraic

Comes with hard case and reference card

In 2018, I reviewed the fx-55 Plus: https://edspi31415.blogspot.com/2018/08/review-casio-fx-55-plus.html

Right now there are plenty of fx-55 (original keyboard) for sale on auction sites for eBay at really inexpensive prices, sometimes as low as about $2.00.

**Target Audiences**

* Elementary and middle school students

* Anyone who wants a few more functions than a regular four-function calculator, but not a scientific calculator

* You want a calculator with an emphasis on fractions

**Keyboard**

The fx-55 Fraction Mate does not have a shift key. Some of the keys are:

[ + ], [ - ], [ × ], [ ÷ ]: Arithmetic keys

[ ( ], [ ) ]: Parenthesis keys

[ x^y ]: Power key with a caret indicator on the screen

[ 1/x ]: Reciprocal

[ RAN# ]: 3 digit random number between 0 and 1

[ FIX ]: Fix setting. For float setting, press [ FIX ] [ . ]

[ RND ]: Round number to fixed setting internally

[ 10^x ]: Antilog function

[ X ←→ Y ]: Switch operators

[ X ←→ M]: Exchange number in the display with number in memory

[ % ]: Percent key, see below

[ > ]: Backspace key

[ a ], [ b/c ]: Fraction entry keys

[ F ←→ D ]: Fraction/decimal conversion

[ a b/c ←→ d/c ]: Improper/proper fraction conversion

[ SIMP ]: Fraction simplification key

[ ÷R ]: Integer division, with quotient and remainder. If both numbers are positive, then remainder acts as a modulo operator

[ √ ]: square root

[ x^2 ]: square function

Integer Division

Pressing [ ÷R ] will return both the quotient and remainder of a division calculation. If both numbers are positive, then the remainder is the modulo.

Example: 55 [ ÷R ] 12 returns 4 R 7. Then 55 = 7 MOD 12.

Percent Key

To add % to n, press:

n [ × ] p [ % ] [ + ]

To subtract % from n, press:

n [ × ] p [ % ] [ - ]

Simplify Key

The [ SIMP ] key simplifies fractions when possible. The factor used to simplify the fraction is briefly displayed. All fractions on the fx-55 FRACTION MATE are simplified manually.

Example: 1450/2900 =

1450 [ b/c ] 2900 [ = ]

Display: = 1450/2900 Simp

The Simp indicator means the fraction can be simplified.

[ SIMP ]

2 brifely displays before 725/1450 Simp

Repeated presses of [ SIMP ]:

5, 145/290 Simp

5, 29/58 Simp

29, 1/2

Order of Operations

The fx-55 follows the order of operations. This is great for students in algebra.

Example:

3 [ + ] 9 [ × ] 11 [ = ] returns 102 (multiplication/division first, then addition/subtraction)

**Verdict**

I like the fx-55 Fraction Mate. It has a lot of additional functions that beyond the traditional four-function calculator: parenthesis, powers, reciprocal, fractions. The display and the numbers are big. I like how the arithmetic and power functions are displayed. Worth the buy.

Casio Ledudu's page for fx-55, including the manual: https://casio.ledudu.com/pockets.asp?type=1176&lg=eng

Eddie

All original content copyright, © 2011-2021. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

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