PassFinder vs (Open Source) Mental Math
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
PassFinder
Track the International Space Station's visible passes over your location. Receive precise timing information to observe the ISS with the naked eye.
- ISS pass tracking
- Visible pass notifications
- Naked-eye observation guidance
- Location-based timing
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See the International Space Station as it passes overhead! You'll get that chance by knowing exactly when the ISS is going to pass over your location and is visible to the naked eye.
(Open Source) Mental Math
This application offers a free, open-source platform for practicing mental arithmetic. It features timed tests, custom drills, and a comprehensive library of mental math tricks. All content is available offline without ads or paywalls.
- Timed arithmetic tests
- Customizable drills
- Mental math tricks library
- Offline progress tracking
- Multiple operation types
- Fast session interface
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A free, open-source mental math trainer. No ads, no paywalls, no locked content — every exercise and difficulty is included. Sharpen your arithmetic with quick timed tests, custom drills, and a library of mental-math tricks. Everything runs offline and your progress stays on your device. FEATURES Timed Tests A daily 60-second challenge plus sprints, a two-minute marathon, per-operation tests, and a hard mixed test — each with best scores. Custom Trainer Pick a number domain (Times tables, Natural, Decimal, Money, Huge), choose one or more exercises, and set per-exercise difficulty from Easy to Super hard. All the Operations Addition, subtraction, multiplication, division, squares, square roots, fractions, percentages, and modulo. Mental Math Tricks Dozens of step-by-step tricks for faster addition, subtraction, multiplication, division, and squares — with worked examples and favorites. Progress Tracking Solved totals, accuracy, best run, daily streak, longest streak, and a weekly activity view. Fast Sessions An on-screen keypad with instant answer checking, haptics, and sound. No ads. No paywalls. No account required. 100% Open Source The complete source code is public - see it, audit it, or contribute at https://github.com/Open-Apps-Studio/mental-math
Screenshots
Verdict
PassFinder and (Open Source) Mental Math both sit at 3.1 stars, but that hides the real split: 39% of PassFinder's written reviews are positive against 0% of (Open Source) Mental Math's. PassFinder also leads on ratings volume (30 vs 2). (Open Source) Mental Math's advantage is iOS requirement (16.4 vs 18.0). On price, rating, update cadence and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 3.1 for PassFinder against 3.0 for (Open Source) Mental Math. That said, the two scores are not equally well evidenced: PassFinder has 30 ratings behind it against 2, so its average is the more settled of the two. Written reviews are what separate them: 39% of PassFinder's written reviews are positive against 0% of (Open Source) Mental Math's.
PassFinder ships an update every 3 months, (Open Source) Mental Math every 2 months. The most recent releases landed on September 28, 2026 and September 19, 2026 respectively.
| Parameter | PassFinder | (Open Source) Mental Math |
|---|---|---|
| Price | Free | Free |
| Rating | 3.1 (30 ratings) — better | 3.0 (2 ratings) |
| Positive reviews | 39.0% of reviews — better | 0.0% of reviews |
| Number of ratings | 30 — better | 2 |
| Update frequency | Every 3 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 18.0 | 16.4 — better |
| Further details — not scored | ||
| Size | 5 MB | 40 MB |
| Age rating | 4+ | 4+ |
| Developer | Christian Hansen | AHMET EMRE DEDELER |
Customer experience
PassFinder
(Open Source) Mental Math
In-app purchases
PassFinder
No in-app purchases
(Open Source) Mental Math
No in-app purchases
Questions
Is PassFinder free?
Is (Open Source) Mental Math free?
Which has better reviews, PassFinder or (Open Source) Mental Math?
Do PassFinder or (Open Source) Mental Math have ads?
Which is updated more often, PassFinder or (Open Source) Mental Math?
Other comparisons
