GravLens3 vs Zetamac Arithmetic Practice
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
GravLens3
Simulate the effects of gravitational lensing on your iPhone or iPad. Adjust lens parameters and apply distortions to your photos or live camera feed. Share your creations or project them for educational purposes.
- Simulate Hubble Space Telescope images
- Adjust lens size and ellipticity
- Distort photos from library or camera
- Live real-time lensing view
- AirPlay and external monitor support
- Save and share distorted images
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Gravitational lensing is a remarkable astrophysical phenomenon, where the light of a distant galaxy is bent by a massive foreground galaxy. Now you can simulate the effect of a gravitational lens on your iPhone or iPad! With GravLens3, a remarkable and educational tool you can: * Simulate Hubble Space Telescope images of strong gravitational lenses * Adjust the size and ellipticity of the lens model * See the distortion on a picture from your photo library or camera * Save the image, tweet it, post to Facebook, or print it * Live View: view the world through a gravitational lens! Real-time lensing with your camera. * Airplay and external monitor support. Broadcast your lensing to an external projector or Apple TV. Great for lectures! * Retina display, iPhone 6/6 plus all supported.
Zetamac Arithmetic Practice
This app offers mental math practice tailored for quantitative finance professionals. It focuses on improving calculation speed and accuracy for complex numerical problems.
- Mental math practice
- Quantitative finance focus
- Calculation speed improvement
- Accuracy enhancement
- Numerical problem solving
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Zetamac - A mental math practice app used in the Quantitative Finance world.
Screenshots
Verdict
The clearest difference is rating: Zetamac Arithmetic Practice at 4.7 against GravLens3's 3.7. Zetamac Arithmetic Practice also leads on update cadence (daily vs every 17 months) and ratings volume (19 vs 6). GravLens3's advantage is iOS requirement (6.1 vs 17.5). On price, review sentiment, ads and in-app purchases 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.
Zetamac Arithmetic Practice holds the better App Store score, 4.7 against 3.7. Both are backed by a comparable volume of ratings — 6 and 19 respectively. Written reviews point the same way: 80% of GravLens3's written reviews are positive against 83% of Zetamac Arithmetic Practice's.
GravLens3 ships an update every 17 months, Zetamac Arithmetic Practice daily. The most recent releases landed on October 23, 2026 and October 30, 2026 respectively.
| Parameter | GravLens3 | Zetamac Arithmetic Practice |
|---|---|---|
| Price | Free | Free |
| Rating | 3.7 (6 ratings) | 4.7 (19 ratings) — better |
| Positive reviews | 80.0% of reviews | 83.3% of reviews — better |
| Number of ratings | 6 | 19 — better |
| Update frequency | Every 17 months | Daily — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 6.1 — better | 17.5 |
| Further details — not scored | ||
| Size | 4 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Eli Rykoff | Joseph Ma |
Customer experience
GravLens3
Zetamac Arithmetic Practice
In-app purchases
GravLens3
No in-app purchases
Zetamac Arithmetic Practice
No in-app purchases
Questions
Is GravLens3 free?
Is Zetamac Arithmetic Practice free?
Which has better reviews, GravLens3 or Zetamac Arithmetic Practice?
Do GravLens3 or Zetamac Arithmetic Practice have ads?
Which is updated more often, GravLens3 or Zetamac Arithmetic Practice?
Other comparisons
