Comparison

Gaussus vs LetterRack

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

Head to head
About

Gaussus

This calculator app grants users a superpower to predict numbers thought of by spectators. It's designed for mentalists and magicians to perform astonishing feats, like revealing a spectator's chosen number or a significant date in advance.

Highlights
  • Predict spectator's thought-of number
  • Reveal pre-written numbers on calculator
  • Guess birth dates
  • Perform advanced mentalism effects
  • Calculator with superpower capabilities
Features
Read full description

Predict any number a spectator is thinking of - and much more. GAUSSUS is a calculator that gives you a superpower. A new tool built especially for mentalists, magicians, and anyone who wants to leave people absolutely amazed. Here are just some of the effects you can perform with GAUSSUS: 1. A spectator thinks of a random number - any number - and you reveal that you had already written it in advance on the calculator on your iPhone. 2. Two spectators (or more) think of different random numbers, and you reveal that you had already written the final total in advance on the calculator. 3. A spectator thinks of the birth date of someone close to them, and you reveal that you knew the date in advance. The possibilities are endless.

About

LetterRack

Features
Read full description

LetterRack. The Mentalist's Secret Weapon. Mentalism lives on one thing: focus. LetterRack gives your spectator exactly what their mind needs to lock onto a thought. Three powerful effects, one elegant tool: A spectator thinks of a random word generated by the app. The mentalist reads their mind. A spectator unscrambles an anagram and focuses on the hidden word. The mentalist reads their mind. A spectator freely chooses any word. The mentalist reads their mind. Three different paths. One impossible outcome. Full control for the performer: LetterRack gives mentalists full control over their letter sets, preparing, organizing, customizing, and cycling through words with precision, so the performer can focus entirely on the audience, not the mechanics. Instant sharing, zero friction: Generate a QR code in seconds and let your spectator scan it with their iPhone. No app download required. They land directly via App Clip, turning their own phone into part of the effect. Always within reach: A Home Screen widget keeps your current word visible at a glance, ready the moment you need it. They think it. You know it. Word lists currently available in English only. Additional languages coming in future updates. The app is free to download and try with up to 5 words. The widget and Apple Watch complication are free to install but show only the first letter of the word. Full word display, App Clip, custom word lists, and advanced word management require an Xtremagic Pass subscription or one-time purchase.

Screenshots

Gaussus3 screens
LetterRack4 screens

Verdict

The call

The clearest difference is price: LetterRack at Free against Gaussus's $29.99. Gaussus's advantage is in-app purchases (none vs 3) and update cadence (every 2 days vs every 3 weeks). On 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

CostPrice · In-app purchases · Ads · Monetization

LetterRack is free to download; Gaussus costs $29.99 up front. LetterRack sells 3 in-app purchases, starting at $3.99 per month. Gaussus asks for nothing beyond the download.

UpkeepUpdate frequency

Gaussus ships an update every 2 days, LetterRack every 3 weeks. The most recent releases landed on October 9, 2026 and October 12, 2026 respectively.

Scorecard4 real differences · 5 level
Gaussus versus LetterRack: the parameters behind the verdict, then further details
ParameterGaussusLetterRack
Price$29.99Free — better
Rating1.0 (1 ratings) — better—
Number of ratings1 — better—
Update frequencyEvery 2 days — betterEvery 3 weeks
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaid—
DevicesiPhone, iPodiPhone, Apple Watch
Requires iOS15.6 — better26.4
Further details — not scored
Size50 MB28 MB
Age rating4+4+
DeveloperOmry IshaiVincent Launay

In-app purchases

None

Gaussus

No in-app purchases

3 purchases

LetterRack

Subscriptions2
  • Xtremagic Pass$3.991 Month
  • Xtremagic Pass$24.991 Year
One-time1
  • Full Access (One-Time Purchase)$7.99

Questions

Is Gaussus free?
Gaussus costs $29.99, with no in-app purchases.
Is LetterRack free?
LetterRack is free to download, with in-app purchases available.
Do Gaussus or LetterRack have ads?
Neither Gaussus nor LetterRack shows ads.
Which is updated more often, Gaussus or LetterRack?
Gaussus ships an update every 2 days, and LetterRack every 3 weeks. Most recently, Gaussus was updated on October 9, 2026 and LetterRack on October 12, 2026.

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