# 往日之事 vs Probability

The clearest difference is price: Probability at Free against 往日之事's $0.29. Probability also leads on update cadence (every 10 days vs every 9 months). 往日之事's advantage is in-app purchases (none vs 1). On review sentiment, ads, device support and iOS requirement there is nothing between them.

Probability is free to download; 往日之事 costs $0.29 up front. Probability sells 1 one-off in-app purchase. 往日之事 asks for nothing beyond the download.

往日之事 ships an update every 9 months, Probability every 10 days. Both last shipped on November 3, 2026.

## The numbers

| Metric | 往日之事 | Probability |
| --- | --- | --- |
| Price | $0.29 | **Free** |
| Rating | — | **[1.0 (1 ratings)](https://appshunter.io/ios/app/probability-easy-and-practical/id1625073969/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | 0.0% of reviews | 0.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 9 months | **Every 10 days** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 5 MB | 166 MB |
| Requires iOS | 14.0 | 14.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [伟 曹](https://appshunter.io/developer/881060499) | [Man Hung Sun](https://appshunter.io/developer/1471605573) |

## What reviewers say

### 往日之事

[App page](https://appshunter.io/ios/app/id1564610369)

Explore significant historical events that occurred on any given day. Discover world-changing moments and see if any important dates align with your own birthday.

**Highlights:** Daily historical events, World-changing historical moments, Event significance, Birthday date correlation

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### Probability

[App page](https://appshunter.io/ios/app/probability-easy-and-practical/id1625073969)

Enhance your decision-making skills by learning to assess probabilities with this app. It offers formulas for problem-solving, note-taking capabilities, and interactive tools like dice and coin tosses for practical learning.

**Highlights:** Probability assessment, Decision-making improvement, Problem-solving formulas, Personalized notes, Dice and coin toss simulations

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Upgrade | $0.99 | one-time |


## Frequently asked questions

### Is 往日之事 free?

往日之事 costs $0.29, with no in-app purchases.

### Is Probability free?

Probability is free to download, with in-app purchases available.

### Do 往日之事 or Probability have ads?

Neither 往日之事 nor Probability shows ads.

### Which is updated more often, 往日之事 or Probability?

往日之事 ships an update every 9 months, and Probability every 10 days. Most recently, 往日之事 was updated on November 3, 2026 and Probability on November 3, 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.*