Comparison

Re vs NBackCalc

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Re

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“Re:Num7” Welcome to the app! This app challenges your working memory. [Magic Number 7±2] It is believed that we use temporary memory, or “working memory,” to remember information like numbers temporarily—especially when they have no particular meaning in sequence—such as when dialing a phone number from a handwritten note. Cognitive psychology suggests that, while individual differences exist, most people can handle chunks of information—essentially blocks of data—with a capacity of around 7, or 7±2 items. This is known as the “Magic Number 7±2.” This app will help you test the capacity of your working memory. See for yourself if this magic number holds true for you—whether your capacity is larger or smaller. How to play: Present a number with a specified number of digits, hide it, then have the user recall and input the number. If it matches, it's OK. Perform 10 sets of this task and observe the accuracy rate. A perfect game is achieved with all questions correct. Calculate a score based on the number of digits and accuracy rate, and compete with others. Scores can be recorded with a nickname and displayed in a ranking. This is expected to provide the following benefits: ・Gain an estimate of your working memory capacity ・Repeated practice may increase working memory capacity ・Similarly, it may help prevent or slow cognitive decline associated with aging ・Improves concentration, and above all, getting answers right is fun Features: ・Choose your preferred keypad layout for number input: phone layout, calculator layout, or (on iPad) horizontal row layout ・You can select the number of digits, generation method, and display method Digit Count: Each level offers three consecutive digit counts, plus a mode where these three counts are increased in three stages from shortest to longest Generation Method: Choose between a method that minimizes repetition (like drawing cards from a deck) or a completely random method Display Method: Options include showing all digits at once or displaying digits sequentially (step-up). A non-hidden method is also available, but the score will be 0 ・It is divided into four levels based on the range of digit counts. Beginner: Choose 5, 6, or 7 digits, or step-up from 5 to 7 digits. Most players should be able to clear this. Intermediate: Choose 7, 8, or 9 digits, or step-up from 7 to 9 digits. Clearable with effort. Advanced: 9, 10, 11 digits. You can choose step-up from 9 to 11 digits. With effort, some may be clearable. Extra: 11, 12, 13 digits. You can choose step-up from 11 to 13 digits. This likely exceeds human capability. Therefore, it is not locked. Aim to clear even a part of it with effort. ・A tutorial function is provided to make getting started easier. ・While primarily designed for individual play, you can register scores with a custom nickname upon game completion, allowing friendly competition with family or friends. ・We've prepared a mode that's easier to play, though your score will decrease. - Doubles the display time for challenge numbers (score halved) - Displays the C (Clear entry) key to re-enter input (using it reduces that challenge's score by 10%) The challenges themselves are simple and straightforward. However, actually attempting them reveals how difficulty skyrockets with increasing digit counts, offering a fascinating experience.

About

NBackCalc

Features
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NBackCalcは、認知科学で実証されたNバック課題をベースにした計算トレーニングアプリです。 【NBackとは?】 N個前の計算問題の答えを記憶しながら、新しい計算問題を解く二重課題です。「覚える」と「計算する」を同時に行うことで、ワーキングメモリ(作業記憶)を効率よく鍛えられます。 【特徴】 ・1〜10バックまで対応。自分のレベルに合わせて調整可能 ・加算・減算・乗算・除算から使用する演算を自由に選択 ・制限時間・問題数をカスタマイズ ・広告なし・完全無料 【こんな人におすすめ】 ・マルチタスクが苦手な人 ・あたふたしてしまいがちな人 ・物忘れが多いと感じている人

Screenshots

Re4 screens
NBackCalc3 screens

Verdict

The call

The clearest difference is in-app purchases: Re at none against NBackCalc's 1. NBackCalc's advantage is ads (none vs shown) and update cadence (every 2 days vs every 2 months). On price, device support and iOS requirement 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. NBackCalc sells 1 one-off in-app purchase. Re asks for nothing beyond the download.

UpkeepUpdate frequency

Re ships an update every 2 months, NBackCalc every 2 days. The most recent releases landed on October 15, 2026 and October 17, 2026 respectively.

Scorecard3 real differences · 3 level
Re versus NBackCalc: the parameters behind the verdict, then further details
ParameterReNBackCalc
PriceFreeFree
Update frequencyEvery 2 monthsEvery 2 days — better
AdsYesNo — better
In-app purchasesNo — betterYes
DevicesiPhone, iPadiPhone, iPad
Requires iOS17.617.0 — better
Further details — not scored
Size12 MB1 MB
Age rating12+4+
Developer有限会社知識情報研究所YOSHINORI KONNO

In-app purchases

None

Re

No in-app purchases

1 purchases

NBackCalc

One-time1
  • 開発者を応援する$0.99

Questions

Is Re free?
Re is free to download, with no in-app purchases.
Is NBackCalc free?
NBackCalc is free to download, with in-app purchases available.
Do Re or NBackCalc have ads?
Re shows ads; NBackCalc does not.
Which is updated more often, Re or NBackCalc?
Re ships an update every 2 months, and NBackCalc every 2 days. Most recently, Re was updated on October 15, 2026 and NBackCalc on October 17, 2026.

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