# do!book vs 勾配電卓

The clearest difference is update cadence: do!book at every 2 months against 勾配電卓's every 45 months. do!book also leads on iOS requirement (9.0 vs 17.0). On price, 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.

do!book ships an update every 2 months, 勾配電卓 every 45 months. The most recent releases landed on September 27, 2026 and September 28, 2026 respectively.

## The numbers

| Metric | do!book | 勾配電卓 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | — |
| Update frequency | **Every 2 months** | Every 45 months |
| Size | 5 MB | 1 MB |
| Requires iOS | **9.0** | 17.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Digital Office  Japan  Inc.](https://appshunter.io/developer/348581782) | [Takahiro Miyashita](https://appshunter.io/developer/1493701742) |

## What reviewers say

### do!book

[App page](https://appshunter.io/ios/app/dobook/id1459068800)

**Features:** macOS Compatibility

**In-app purchases:** none


### 勾配電卓

[App page](https://appshunter.io/ios/app/1x/id1493701743)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is do!book free?

do!book is free to download, with no in-app purchases.

### Is 勾配電卓 free?

勾配電卓 is free to download, with no in-app purchases.

### Which is updated more often, do!book or 勾配電卓?

do!book ships an update every 2 months, and 勾配電卓 every 45 months. Most recently, do!book was updated on September 27, 2026 and 勾配電卓 on September 28, 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.*