OASIIO FX-911W-C Scientific Calculator

In-Depth Review: OASIIO FX-911W-C Scientific Calculator

Distributed by: Balkumari PL Traders (Nepal)
Model: FX-911W-C
Key Feature Claim: "As Written In Textbook" / "Your 1st Choice Brand!"

Quick Verdict

Rating: ⭐⭐⭐☆☆ (3.2/5)
The OASIIO FX-911W-C is a budget clone heavily inspired by the classic Casio fx-991W series. It works for basic school-level math and science (up to Grade 12), but it is not a professional-grade or exam-board-approved calculator. It offers good value for money if you need a cheap, disposable unit for home practice, but carries significant risk for official exams.

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Key Specifications (from images)

• Model: FX-911W-C

• Power: Two Way Power (Solar + Battery)

• Display Type: S-A.M.P.V. (likely a budget version of Super-Auto Multiple Power View – similar to natural display but may be low resolution)

• Key Features: FMLA (Formula memory), CALC, SOLVE, Base-N (DEC, BIN, OCT, HEX), AND/OR/XOR/XNOR logic.

• Functions seen on keys: Fraction (ab/c), Exponent (EXP), Delete (DEL), Memory (M+, MC, STO).

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Detailed Analysis

1. Build Quality & Keypad

Observation: The calculator has a standard dark grey scientific body with a plastic keypad.
Review:

• Pros: It looks sturdy for its price point. The keys are hard plastic and likely have a tactile "click."

• Cons: Budget clones often have mushy keys that fail to register presses or double-register over time. The labeling is printed (not molded/dual-shot), meaning frequent use can wear off the text around the ALPHA and MODE keys.

• Risk: The two-way power (solar + battery) on cheap units often fails. The solar cell may be cosmetic or low-efficiency, and the battery (usually a single LR44) may leak or die quickly .

2. Display Quality (The "As Written In Textbook" Claim)

Observation: The box claims "As Written In Textbook" and the front labels S-A.M.P.V.
Review: This implies a Natural Display (showing fractions, square roots, integrals as they appear in textbooks).

• Likely Reality: On a budget clone, the display is often a low-contrast, pixelated LCD that works in good light but becomes unreadable in dim rooms or at an angle. It is not as crisp as a genuine Casio Natural Display.

• Test this immediately: Try entering 1/2 + 1/3. If it shows a stacked fraction, it's fine. If it shows 0.5+0.333, the claim is false.

3. Mathematical Capabilities

Intended for: Grade 8–12 (Algebra, Trigonometry, Basic Calculus, Matrices, Base conversions).

What it likely does well:

• Basic arithmetic and scientific notation.

• Trigonometric functions (sin, cos, tan).

• Logarithms and exponentials.

• Single-variable statistics (mean, standard deviation).

• Formula memory (FMLA) for equations like quadratic, area, etc.

What it likely fails at (compared to genuine Casio fx-991 series):

• Complex calculations (no complex number mode).

• Matrix calculations beyond 2x2 (if at all).

• Equation solving (SOLVE is often unreliable on clones).

• Integration/Differentiation – likely absent despite the "991" naming.

• Multi-statement commands (e.g., : to chain operations).

4. Exam & Classroom Risks (Critical!)

 

Issue	Details
Exam Approval	Most education boards (e.g., SLC/SEE in Nepal, CBSE, GCSE) only allow specific models (e.g., Casio fx-82MS, fx-991ES). OASIIO is almost never on the approved list.
Proctored Tests	Invigilators may confiscate it as an "unauthorized device" even if functions are identical.
Teacher Disapproval	Many schools ban generic clones because they can be programmed (some clones hide programmable memory).
Key Legend Wear	With daily use, the printed labels fade within 3–6 months, making it unusable for exams.

⚠️ Do NOT bring this to an official board exam (SEE, HSEB, IIT, JEE, etc.) unless you have written confirmation it's allowed.

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Comparison: OASIIO FX-911W-C vs. Genuine Casio fx-991MS / fx-991ES

 

Feature	OASIIO FX-911W-C	Casio fx-991MS (Genuine)	Casio fx-991EX (Classwiz)
Price	~$5–8 USD (NPR 600–1000)	~$15–20	~$25–30
Build Quality	Poor (wears quickly)	Good (lasts 5+ years)	Excellent
Display Clarity	Low contrast, narrow angle	High contrast, reliable	High-res natural display
Natural Display	Claimed but usually fake	Yes (on ES models)	Yes
Complex Numbers	No	Yes (fx-991MS/ES)	Yes
Matrix/Vector	No	Limited (2x2 only)	Full
Exam Approval	No	Yes (most boards)	Yes
Software Bugs	Common (wrong results)	Very rare	None

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Known Issues with Budget Clones (Based on user reports)

1. Order of operations errors – e.g., 6/2(1+2) may give 1 or 9 unpredictably.

2. Memory loss – Switching modes deletes stored values.

3. Slow response – 1–2 second lag on trig functions.

4. Display ghosts – Faint digits remain after clearing.

5. Solar cell – May be fake plastic with no actual circuit.

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Who Should Buy This?

✅ Buy only if:

• You need a very cheap calculator for home practice only.

• You are okay with replacing it every 6–12 months.

• You understand it may give wrong answers for complex expressions.

• You will not use it in any official exam.

❌ Avoid if:

• You are preparing for SEE, HSEB, IOE, JEE, NEET, or any government exam.

• You need reliability (engineering, accounting, science lab work).

• You want a calculator that lasts more than 1 year.

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Final Recommendation

Spend slightly more on a genuine Casio fx-82MS (or fx-991MS).
The price difference is small, but the difference in reliability, exam acceptance, and lifespan is huge.

If you already own the OASIIO:

1. Test it: Perform 5 + 2 × 3 → should show 11 (not 21).

2. Check display angles – tilt it 30° up/down. If text vanishes, it's poor quality.

3. Never rely on it for exams. Keep a known genuine model as backup.

Final Verdict:
"A functional but risky clone. Fine for scratching notes at home. Dangerous for exams or serious work."

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