Retro Review: Casio fx-55 Fraction Mate
Model: fx-55 Fraction Mate
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
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.
* 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
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
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.
To add % to n, press:
n [ × ] p [ % ] [ + ]
To subtract % from n, press:
n [ × ] p [ % ] [ - ]
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
Order of Operations
The fx-55 follows the order of operations. This is great for students in algebra.
3 [ + ] 9 [ × ] 11 [ = ] returns 102 (multiplication/division first, then addition/subtraction)
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
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