f(x) vs Constant Challenge
Price, ratings, monetisation and update history for both games, side by side — with what reviewers say about each.
f(x)
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[ルール説明] 1.ターンが始まるとxの値がランダムで与えられる. 2.味方キャラはそれぞれ技(関数)を持っており,誰のどの技を発動するかを選ぶ.選んだ技に応じてxの値が変化する.これを3キャラ分行う. 3.味方キャラの値のうち,正の値は攻撃力に,負の値は回復力になる. 4.敵が行動してターン終了.まあやれば分かる(はず...!).
Constant Challenge
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Constant Challenge is a training app designed to help you memorize mathematical constants like π (pi) and e while testing your skills through various challenge modes. Each constant offers the same set of game modes, allowing you to practice, compete, and improve your memory and speed. Features: - Practice Mode: Learn and memorize digits at your own pace - Time Attack Mode: Enter as many correct digits as possible within a time limit - Stage Mode: Progress through structured levels of increasing difficulty - Local Battle Mode: Competitive play possible Track your performance, challenge yourself, and aim for high scores. Perfect for students, math enthusiasts, and anyone who enjoys memory challenges. Note: This app focuses on memorization and training of mathematical constants.
Screenshots
Verdict
The clearest difference is in-app purchases: f(x) at none against Constant Challenge's 3. f(x) also leads on iOS requirement (15.0 vs 26.0). Constant Challenge's advantage is update cadence (every 2 days vs monthly). On price, ads 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
Both are free to download. Constant Challenge sells 3 one-off in-app purchases. f(x) asks for nothing beyond the download.
f(x) ships an update monthly, Constant Challenge every 2 days. The most recent releases landed on September 25, 2026 and September 28, 2026 respectively.
| Parameter | f(x) | Constant Challenge |
|---|---|---|
| Price | Free | Free |
| Update frequency | Monthly | Every 2 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.0 — better | 26.0 |
| Further details — not scored | ||
| Size | 77 MB | 16 MB |
| Age rating | 12+ | 4+ |
| Developer | Ryo Matsumoto | Kaname Inoue |
In-app purchases
f(x)
No in-app purchases
Constant Challenge
- Unlock the Square Root of 2 (√2)$0.99
- Unlock the Golden Ratio (φ)$0.99
- Unlock the Euler–Mascheroni (γ)$0.99
Questions
Is f(x) free?
Is Constant Challenge free?
Do f(x) or Constant Challenge have ads?
Which is updated more often, f(x) or Constant Challenge?
Other comparisons
