Appworthy
App Store
Version 1.9.3 · 2026-10-23
- Added Daily Challenge with 10 new math questions every day. - Track your personal progress and compete on the 7-day leaderboard.
App Store rating4.6★445 ratings
PriceFreeIn-app $0.99–$14.99
Age4+Store age rating
Size28 MBiPhone download
CategoryEducation
DeveloperDinh Phuc
What we found
Full reportToo little checked to say Store information only. We haven’t analysed this app or read its reviews yet.
Money
- Free to download · in-app purchases $0.99–$14.99 (5 listed). Monthly plans $0.99 (about $12 a year), $1.99 (about $24 a year) and $2.49 (about $30 a year); yearly plan $7.99.
- If you subscribe through the store, cancel in iPhone Settings → your name → Subscriptions. Deleting the app doesn’t cancel a subscription.
Not yet tested.
The store currently lists version 1.9.3, updated 2026-10-23.
Preview
Store screenshots supplied by the developer.
About this app
Scientific Calculator fx-991 – The Ultimate Math & Science Tool!
Struggling with math problems, equations, or integrals? Need a powerful scientific calculator to solve step-by-step?
With Scientific Calculator fx-991, you can calculate, graph, and find formulas instantly – making learning math, physics, and chemistry easier than ever!
Key Features
+ Step-by-step equation solver – Enter any equation and get a detailed step-by-step solution.
+ Advanced scientific functions – Solve fractions, algebra, derivatives, integrals, trigonometry, and more.
+ Graphing mode – Visualize mathematical functions interactively.
+ Extensive formula library – Access key formulas for math, physics, and chemistry in seconds.
+ Unit converter – Quickly convert between different measurement units.
+ Casio fx-991 inspired interface – A familiar and intuitive experience for students.…
From the developer’s store description.
For developers and the curious
The full report
The evidence, sources, measurements and versions behind every label above.
Findings and evidence
Not yet tested. No analysis has been published for this app. A missing label is not a clean bill of health.
What reviewers report
No review analysis published for this app.
Measurements
“Not assessed” means we could not measure it. It is never a zero and never a pass.
From store data and reviews
Developer replies to reviews
Not assessed
Fewer than 50 reviews scanned — too few to state a rate
Price in the store description
The store description doesn’t list prices (most don’t)
Cancelling, in the store description
The store description doesn’t say how to cancel (most don’t)
Themes reported by reviewers
Not assessed
This app's reviews have not been assessed yet
Five-star share of ratings
80–89% five-star
Arithmetic on the stores' own published rating counts. It says nothing about why the ratings fall where they do.
In the app package we scanned
No package has been scanned for this app, so nothing is published about what it ships. That is an absence of evidence, not a finding.
Sensitive permissions
Not assessed
No package has been scanned for this app
Analytics or tracking SDKs in the scanned package
Not assessed
No package has been scanned for this app
Advertising SDKs in the scanned package
Not assessed
No package has been scanned for this app
How we know
Supporting measurements: not a complete list of possible harms or positives. Measurement vocabulary 1.4 · how these are measured
Versions and dates analysed
Not yet tested. No analysis has been run for this app, so there is no version or date to report.
Store update history
Each store’s release notes, as the developer wrote them. They are the developer’s words, not ours.
Assessment record
- Status
- Not yet tested
- App identifier
scientific-calculator-fx-991- Sources used
- None recorded
- Reviews read
- None recorded
- Package examined
- No package scan
- Human inspection
- Not completed
How we know
- Measurement vocabulary
- 1.4
Store facts
What the stores publish. Store ratings are the stores’ numbers, not Appworthy’s, and are never averaged across stores.
App Store
- Store rating
- 4.58 ★ · 445 ratings
- Version
- 1.9.3
- Updated
- 23 Oct 2026
- Price
- Free · In-app purchases
- Age rating
- 4+
- Size
- 28 MB
- Developer
- Dinh Phuc
- Category
- Education
- Listing price
- Free · In-app purchases
Purchases the store lists
What this app sells
From the store listing. Billing terms are read from each purchase’s name — the stores don’t publish them — so treat them as a strong hint, not a disclosure.
Subscriptions4
Monthly Premium AccessMonthly$1.99
Remove Ads 30 DaysMonthly$0.99
6-Month Premium MembershipMonthly$2.49
Yearly Premium AccessYearly$7.99
Buy once1
HiEdu Pro LifetimeLifetime$14.99
Method and limits
What a missing label means
Not yet tested. No analysis has been published for this app, so there is no method to describe for it yet. A missing label is not a clean bill of health: it means nothing has been read, not that nothing is wrong.
Limits of this report
- A package scan is static. It identifies code and text in one Android build. It does not measure a live ad session, test a deletion request, or count the steps needed to cancel.
- Reviews keep their sample. A review-only charge shows distinct reviewers, the share and the sample size, and is published only once it clears that label’s published threshold. Calibration labels are machine-drafted and not yet confirmed by a person.
- Not assessed is a state. It is never a zero and never a pass.
- A missing label is not a clean bill of health. It means the evidence did not support one, not that the app is problem-free.
Not yet human-reviewed. A human review gives an app hands-on, recorded measurements. None has been run for this app. Hands-on inspections are not yet open.
Request a correction
Write to [email protected], or use the form. Name the finding, the app version and the evidence that needs correcting. Factual corrections are free and never depend on buying anything.