Review: NY-991MS Ewriter Calculator Review (LINGSFIRE)
Price: About $18 - $25 (purchased on Amazon)
Power: Solar with battery (CR2032)
Display: Two lines, numerical and fractions. Numbers can have up to 10 digits.
Calculator with an Electronic Writing Board
The NY-991MS is one of a new breed of calculators to come with a mini electronic writing board attached. For this calculator, the pen is stored in a lower left-hand corner compartment. There is a lock switch at the top of the calculator. If the lock switch is on the left position, the board is unlocked, therefore the board to be erased with the press of a clear button. If the lock switch is on the right, the board is locked and nothing can be erased.
It is the writing board that got me interested in buying this calculator and is a neat feature to write quick notes. So far, the NY-991MS is the most advanced calculator that has this feature.
Other models include (not an all inclusive list):
JEOEUS JEOEUS-005: basic four function calculator
LINGSFIRE: similar to a Casio fx-300 MS
Laelr: similar to a low-cost scientific calculator Sharp EL-501XBGR
On my calculator, the pen was hard to get out (but locks in nicely), so I keep a pen in a separate bag near this calculator.
I love the hard folding case that the NY-991 MS comes in. Not only it looks professional, the case is hard and protects both the calculator and the writing tablet. I also love how large the numbers and functions are on the screen.
Not Quite A Casio fx-115MS
Now let's talk about the functionality. I would place the NY-991 MS somewhere between the Casio fx-300MS and the Casio fx-115MS.
Let's get the ugly out of the way. The manual is terrible. The manual has examples of functions that are not even present, mislabels keys, and has a lot of spelling errors. If this is someone's first calculator, then the person is going to have a rough experience if they tried to follow the manual. Put in some effort and proofread, NewYes.
The NY-991MS has four main modes:
0: COUNT. This is the regular operating mode of the calculator.
1: STAT: One-variable statistics
2: REG: Regression
3: CMPLX: Complex Number arithmetic
While a lot of functions are self-explanatory, some need to be pointed out due to some idiosyncrasies.
The angle setting is a toggle button:
[ D|R ]: switch between degrees and radians. There is a "G" indicator too, but the NY-991MS does not have a gradian mode.
[ 2ndF ] (D←→R): switches between degrees and radians, plus converts the angle in the display.
When the calculator is in degrees mode, there is a "TY" indicator on the screen. I have no idea what TY stands for nor does the manual explain this indicator.
The number format has a three-way toggle button:
[ F/S ] (number): Fixed mode
[ F/S ] [ F/S ] (number): Scientific mode
[ F/S ] [ F/S ] [ F/S ]: Float mode
The [ DMS ] key is dual purpose: entering degree, minute, or second markers during calculations. After the equals key is pressed, the key switches the number between degrees-minutes-seconds and decimal degrees format.
The key sequence [ 2ndF ] ( ←→DEG) does not do anything.
The logarithm keys operate differently from most scientific calculators:
[ log ]: takes the logarithm of any base. The syntax: log(number,base)
[ lg ]: common logarithm
[ ln ] : natural logarithm
The polar/rectangular conversions do not accept parenthesis or a syntax error occurs.
5,3 [ →rθ ] returns r (stored in X) returns = 5.830951895 and θ (stored in Y) returns 30.96375653
(5,3) [ →rθ ] gives an error
Similar with the →xy function. I thought this key was broken or useless until I figured it out by accident. The manual does not show the correct way to use the polar/rectangular conversion.
The key [ A^m_n ] is the permutation key. No idea why this is labeled A. The more appropriately labeled C^m_n is the combination key.
We can store expressions for later evaluation. Press [ 2ndF ] (LRN) to store the expression. Press [ COMP ] to evaluate it. You will be prompted for the variables. The stored expression is erased when the calculator is turned off. There is no solve feature.
Derivative: d/dx( function of X, value)
Definite Integral: ∫( function of X, lower limit, upper limit)
There is this weird arrangement of variables. A, B, C, D are in one line while X, Y, and Z are on the 2nd row. In this mode we have a bug: whenever a value is stored in A, the display returns 0. The value is retained in A though.
Want to enter numbers in scientific notation? Press [ 2ndF ] ( Exp ) to get the E.
One variable stats are entered using the [ DATA ] button. What I like about the statistics mode is that parameters are on the keyboard, that can be accessed by the [ ALPHA ] key. However, s_x does NOT return the sample deviation, but the population deviation. Likewise, (s_x)^2 returns the population variance.
There are six regressions, which the variables are mislabeled in the manual. Here are the true regression equations used:
1. Lin: Linear Regression, y = a*x + b
2. Quad: Quadratic Regression, y = a*x^2 + b*x + c
3. Inv: Inverse Regression, y = a/x + b
4. Pwr: Power Regression, y = b * x^a
5. Exp: Exponential Regression, y = b * e^(a*x)
6. Log: Logarithmic Regression, y = a*ln x + b
In essence, other than quadratic regression, the variable a is the slope and the variable b is the y-intercept.
The [ ALPHA ] key is needed to use the prediction functions x-hat and y-hat.
The complex number mode is, as expected, limited. Allowable operations are the arithmetic functions, the reciprocal, and the square functions. Enter the imaginary part with the [ i ] button.
Results are shown on part at a time between the real and imaginary part. Press [ 2ndF ] [ i ] (←.→) to switch between the real and imaginary parts. There is another key that is exclusive to this mode:
[ |R| ]: absolute value. This operates only after the calculation is completed by pressing the equals key.
[ 2ndF ] (ARG): argument. Likewise, this operates only after the calculation is completed by pressing the equals key.
The manual mentions a conjugate function, which isn't present on the calculator.
This calculator had potential and unfortunately, with the arrangement of keys, mislabeling of the deviation and variance, the unusual syntax of some functions, and the horrible manual, I cannot recommend this calculator unless you are an expert user. I was able to figure out the functions due to the fact I had a Casio calculator to compare results. The electronic board and the beautiful folding case, while very nice, may not be enough to make up for the faults for some. Not recommended for a beginner at all, especially if the user has to depend on the manual to use it.
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