R21 vs Math Orbs
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
R21
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R21 is a new six-level reading series carefully designed to help young learners develop the skills they’ll need to succeed in the 21st century. Each book covers a range of topics and makes use of the latest Content and Language Integrated Learning (CLIL) methods to ensure they’ll appeal to young children and have a connection to children’s wider studies and experiences. With R21, reading is fun, inspiring as well as informative, and children will not only develop their reading competence but also become a great thinker in the 21st century.
Math Orbs
This app offers Grade 1-6 algebra practice for children, allowing parents to track progress and identify areas of difficulty. It features interactive quests, collectible orbs, and a virtual scratchpad for calculations, making learning engaging and eliminating the need for workbooks.
- Grade 1-6 algebra practice
- Parental progress tracking
- Identify areas of struggle
- Interactive quests
- Collectible orbs
- Virtual scratchpad
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Math Orbs is a math app that lets parents track their children's progress through Grade 1—6 algebra as they practice what they've learned. - Say goodbye to grading your child’s answers in workbooks! - Grades 1—6 algebra: never buy that “next grade” workbook again! - Scribbles for incorrect answers are recorded, helping you identify where and why they are struggling. - Track their overall progress and performance with statistics such as overall percentage score, time taken per quest, and time spent per question. Your kids will: - Practice Grade 1–6 arithmetic that becomes progressively more challenging, including addition, subtraction, multiplication, division, decimals, and fractions. - Unlock beautiful orbs every time they pass a quest. Try to collect them all! - Use the built-in virtual scribble pad for calculations—no paper or pencil needed! - No longer able to peek at the answers from the back of workbooks! Download Math Orbs today and help your kids become math wizards!
Screenshots
Verdict
The clearest difference is price: R21 at Free against Math Orbs's $0.99. R21 also leads on iOS requirement (9.0 vs 13.0). Math Orbs's advantage is update cadence (weekly vs every 3 months). On ads, in-app purchases and device support 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
R21 is free to download; Math Orbs costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
R21 ships an update every 3 months, Math Orbs weekly. The most recent releases landed on October 10, 2026 and October 2, 2026 respectively.
| Parameter | R21 | Math Orbs |
|---|---|---|
| Price | Free — better | $0.99 |
| Rating | — | 5.0 (2 ratings) — better |
| Number of ratings | — | 2 — better |
| Update frequency | Every 3 months | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 9.0 — better | 13.0 |
| Further details — not scored | ||
| Size | 114 MB | 72 MB |
| Age rating | 4+ | 4+ |
| Developer | CAVES BOOKS LTD. | Knowledge Vortex, LLC |
In-app purchases
R21
No in-app purchases
Math Orbs
No in-app purchases









