# SpeedJack 21 vs Probability(Math Drills)

The clearest difference is ads: Probability(Math Drills) at none against SpeedJack 21's shown. On price, update cadence, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

SpeedJack 21 ships an update fortnightly, Probability(Math Drills) every 3 weeks. The most recent releases landed on September 16, 2026 and September 26, 2026 respectively.

## The numbers

| Metric | SpeedJack 21 | Probability(Math Drills) |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/speedjack-21/id1511287771/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | **Fortnightly** | Every 3 weeks |
| Monetization | Ad-supported | — |
| Size | 86 MB | 28 MB |
| Requires iOS | 13.0 | **12.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 12+ | 4+ |
| Developer | [KwangRim Ahn](https://appshunter.io/developer/1511287770) | [郷 田村](https://appshunter.io/developer/1574588679) |

## What reviewers say

### SpeedJack 21

[App page](https://appshunter.io/ios/app/speedjack-21/id1511287771)

Practice your blackjack basic strategy with this educational app. Achieve consecutive correct answers to rank your time record on the server and improve your casino winning average.

**Highlights:** Blackjack basic strategy practice, Consecutive correct answer challenge, Server-based time ranking, Improve casino winning average, User sign-in required for challenges

**Features:** macOS Compatibility

**In-app purchases:** none


### Probability(Math Drills)

[App page](https://appshunter.io/ios/app/probabilitymath-drills/id1632889899)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is SpeedJack 21 free?

SpeedJack 21 is free to download, with no in-app purchases.

### Is Probability(Math Drills) free?

Probability(Math Drills) is free to download, with no in-app purchases.

### Do SpeedJack 21 or Probability(Math Drills) have ads?

SpeedJack 21 shows ads; Probability(Math Drills) does not.

### Which is updated more often, SpeedJack 21 or Probability(Math Drills)?

SpeedJack 21 ships an update fortnightly, and Probability(Math Drills) every 3 weeks. Most recently, SpeedJack 21 was updated on September 16, 2026 and Probability(Math Drills) on September 26, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*