Comparison

N4 vs Uncertainty Calculator

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

Head to head
About

N4

Master JLPT N4 grammar with this app. It organizes sentence patterns with clear explanations in Chinese and provides practice questions. Easily mark difficult words for review to improve your exam performance.

Highlights
  • JLPT N4 grammar organization
  • Detailed sentence pattern explanations
  • Chinese language explanations
  • Word marking for review
  • Over 300 practice questions
Features
Read full description

1. The grammatical explanations are aligned with the new Japanese Language Proficiency Test standards, including various sentence patterns, and fully comply with the new test guidelines. Contains over 300 grammar practice questions. 2. Allows learners to easily master the material in their spare time. 3. Compiles all sentence patterns required for the JLPT N4 reading section, organized in a simple and easy‑to‑understand way, with detailed explanations of each pattern. No professional grammar terminology beyond the learning scope is used. The app can be comfortably operated with one hand, making learning more efficient. 4. Includes detailed explanations. Through repeated practice with various question types, learners can achieve complete mastery. Whenever they encounter difficulties, they can always review the explanations to fully grasp the meaning and usage of each grammar pattern. 5. When encountering difficult or hard‑to‑memorize vocabulary, users can mark words with three different types of symbols. By tapping on any symbol‑marked word, they can repeatedly reinforce their practice. 6. In addition to providing Chinese translations for the example sentences within the grammar explanations, the app also allows users to check explanations anytime they encounter something they don't understand. This effectively helps learners master key grammar points and sentence structures, strengthening their overall grasp of grammar patterns. 7. Supports iPhone 4 and above, as well as all iPad models.

About

Uncertainty Calculator

This app allows users to perform error propagation calculations for mathematical expressions involving uncertain variables. It supports absolute and relative error inputs, various functions, and trigonometric calculations in degrees or radians. The tool helps ensure accurate reporting of results based on estimated errors.

Highlights
  • Error propagation calculations
  • Absolute and relative error input
  • Support for mathematical functions
  • Trigonometric calculations (degrees/radians)
  • Variable combination in expressions
  • Significant figure guidance
Features
Read full description

Uncertainty Calculator evaluates the error propagation throughout the mathematical expressions comprised of variables of uncertain value. The application allows input of up to three value-error pairs (A, B and C), that can be used as a parameters in the final expression. Error values should be provided in absolute (100 +/- 5) or in relative format, the latter should appear in percent format (100 +/- 5%). The evaluated expression can include numerous functions, that provided by row of the appropriate buttons. Components and functions can be added directly to the expression field by pressing the corresponding buttons. To encompass expression into the preset formula, select the expression and press the corresponding formula button. Particular attention should be paid to placing brackets to avoid equation ambiguity. The application deals with independent, random errors. So if this is a case never use A + A, but rather 2*A and never A*A*A but rather A^3! Obviously, different parameters can be combined in any way (A+B or C *A^2 .. is perfectly fine). Angles for trigonometric functions can be provided in degrees or radians, and that should be reflected by setting a yellow button to "DEG" or "RAD". Bear in mind the importance of units in any of calculations! Implementation Examples: 1.The charge passing through an electrical circuit is defined by: Q = I * t, where I is the current and t is the time. Calculate the total charge value when a current of 0.15 ± 0.01 A passes through the circuit for 120 ± 1 s: Input: A = 0.15 ± 0.01, B = 120 ± 1 The final expression will be A*B, and press Calculate: The final value will be: 18 ± 1.2 Thus, it can be reported the total charge as 18 C ± 1 C. Important! One should only report as many significant figures as are consistent with estimated error! So the value should be rounded to the rightmost decimal place at which error applies. 2. A ball is tossed straight up into the air with initial speed vo = (4.0± 0.2) m/s. After a time t = (0.60 ± 10%) s, the height of the ball is h = vo*t - 0.5gt^2 = 0.636 m (g = 9.80 m/s^2). What is the value and uncertainty of height? Input: A = vo = 4.0 ± 0.2, and B = t = 0.60 ± 10%, then the final expression should be: A*B – 0.5*9.8*B^2 The final value will be: 0.6 ± 0.4 (meters).

Screenshots

N44 screens
Uncertainty Calculator4 screens

Verdict

The call

The clearest difference is price: Uncertainty Calculator at $3.99 against N4's $9.99. Uncertainty Calculator also leads on iOS requirement (17.0 vs 26.0). On update cadence, ads, in-app purchases and monetization model 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

N4 costs $9.99 and Uncertainty Calculator $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

N4 ships an update every 6 months, Uncertainty Calculator every 3 months. The most recent releases landed on September 20, 2026 and September 14, 2026 respectively.

Scorecard2 real differences · 8 level
N4 versus Uncertainty Calculator: the parameters behind the verdict, then further details
ParameterN4Uncertainty Calculator
Price$9.99$3.99 — better
Rating5.0 (1 ratings) — better
Positive reviews0.0% of reviews
Number of ratings1 — better
Update frequencyEvery 6 monthsEvery 3 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPadiPhone, iPad
Requires iOS26.017.0 — better
Further details — not scored
Size19 MB1 MB
Age rating4+4+
DeveloperYamase & Touwa Japanese InsitituteRoman Volinsky

Customer experience

N4

Written reviews2 reviews
Positive0.0%
Neutral50.0%
Negative50.0%

Uncertainty Calculator

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

N4

No in-app purchases

None

Uncertainty Calculator

No in-app purchases

Questions

Is N4 free?
N4 costs $9.99, with no in-app purchases.
Is Uncertainty Calculator free?
Uncertainty Calculator costs $3.99, with no in-app purchases.
Do N4 or Uncertainty Calculator have ads?
Neither N4 nor Uncertainty Calculator shows ads.
Which is updated more often, N4 or Uncertainty Calculator?
N4 ships an update every 6 months, and Uncertainty Calculator every 3 months. Most recently, N4 was updated on September 20, 2026 and Uncertainty Calculator on September 14, 2026.

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