# Calculation Training: Ottugi — Mental Math & Estimation

> Timed mental arithmetic and estimation trainer with graded sessions. (iPhone/iPad app by JinWook You.)

- Source: https://appshunter.io/ios/app/calculation-training-ottugi/id6751992934 (this page in markdown: same URL + `.md`)
- Developer: [JinWook You](https://appshunter.io/developer/1837824846)
- Category: Education, Productivity
- Price: Free
- Age rating: 4+
- Requires: iOS 16.0 · 3 MB
- Languages: Korean, American English
- Released: 2025-09-19
- Data updated: 2026-10-13
- Monetization: freemium
- User reviews in markdown: https://appshunter.io/ios/app/calculation-training-ottugi/id6751992934/reviews.md

## What is Calculation Training?

Calculation Training is a timed trainer for mental arithmetic and estimation.

ARITHMETIC (all free)
• Pick the digits and the operation, from 1-digit to 4-digit numbers
• Exam Mode mixes addition, subtraction, multiplication, and division at random

COMPARISON
• No exact answers needed. Just decide which side is bigger, as fast as you can
• 7 types: fractions, products, multiples, growth rates, decrease rates, sums, and multi-term sums
• Unlimited generated problems, with a free sample of every type

GRADES
• Every session is graded from S to D by your seconds per question
• Wrong answers add a time penalty, so guessing fast does not pay off

PAST EXAM NUMBERS
• Comparison items taken from real Korean civil-service data-interpretation exams

Supports English and Korean, light and dark mode.
Premium is an auto-renewing subscription that unlocks full Comparison and Past Exam training.

## Key features

- Timed mental arithmetic training
- Estimation and comparison challenges
- Multiple arithmetic operations
- Graded sessions with time penalties
- Real exam data for comparison training
- Light and dark mode support

## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/calculation-training-ottugi/id6751992934/reviews.md

### 4/5 — 오답 PDF 다운로드 기능 요청

*2026-06-26*

오답을 앱에서만 확인하니 불편함이 있습니다.

다른 학습 어플들처럼
오답은 PDF 다운로드 할 수 있게 부탁드립니다. 

감사합니다.

### 5/5 — 감사합니다!

*2026-06-12*

책없이도 어디서든 연습할 수 있어서 좋아요 ! 스터디
하며 꾸준히 사용하고 있습니다;)

### 5/5 — 기출훈련 구독했는데 페이지 변동없이 구매하기만 나오네요

*2025-12-13*

어떻게 해결해야하나요?

## Frequently asked questions about Calculation Training

### What is Ottugi's main focus?

Ottugi is a timed trainer designed to enhance mental arithmetic and estimation skills. It offers various modes like Arithmetic, Comparison, and Graded sessions to challenge users.

### What types of arithmetic can I practice with Ottugi?

Ottugi supports practicing arithmetic with numbers ranging from 1-digit to 4-digit. You can choose specific operations or use the Exam Mode which mixes addition, subtraction, multiplication, and division randomly.

### How does Ottugi's Comparison mode work?

In Comparison mode, you don't need exact answers. You quickly decide which side of a comparison is larger. It includes 7 types of comparisons like fractions, products, and growth rates.

### Does Ottugi offer a way to track progress?

Yes, every session in Ottugi is graded from S to D based on your seconds per question. Wrong answers incur a time penalty, discouraging rapid guessing.

### Is Ottugi available on multiple devices?

Yes, Ottugi is supported on both iPhone and iPad devices, offering a consistent experience across Apple's mobile platforms.

### What is the premium subscription for Ottugi?

The premium subscription is an auto-renewing service that unlocks full training for the Comparison and Past Exam modes. The base Arithmetic training is entirely free.

### How often is Ottugi updated?

The latest version of Ottugi was released on October 9, 2026, indicating active development and updates. The app was initially released on September 19, 2025.

### What languages does Ottugi support?

Ottugi supports both English and Korean languages, making it accessible to a wider range of users. It also features both light and dark mode options.

## Version history (last 5 releases)

### 4.0.0 — 2026-10-09

What's new in 4.0.0
• Home tab: your streak, Today's Round, and Today's Picks on one screen.
• Pizzle League: tap "See my rank" after an exam-mode round to see this week's ranking in Pizzle.
• My grades: see your latest grade for each exam mode in My Page.
• Exam mode is now always 20 questions.
• Refined the difficulty and question mix of Comparison drills.
• Fixed 3-digit ÷ 1-digit division often showing 100 ÷ 1.
• Subscriptions: offer terms and Restore Purchases on the paywall, Manage Subscription in My Page.
• VoiceOver now reads calculator keys and fractions.
• Added Lee Jieun's Beopgalpi to recommended apps.

### 3.4.0 — 2026-09-24

• See your study streak on My Page
• Choose a display mode: System, Light, or Dark
• Clearer statistics: a color for each type and separate history for wrong-answer retries
• Retry wrong answers exactly as you first saw them
• Faster launch and more accurate solving times
• Study records are saved more safely and quickly
• Fixed grading errors in some past exam questions and improved purchase/restore messages

### 3.3.0 — 2026-09-21

• 비교훈련·기출훈련을 구독 전에 미리 풀어볼 수 있는 유형별 샘플을 추가했습니다.
• 샘플을 풀면 유형별로 내 풀이 시간과 S등급 기준을 비교해 볼 수 있습니다.
• 등급 기준을 조정했습니다. 분수 비교·나눗셈·기출훈련의 S 기준이 문항당 6.0초에서 4.5초로 바뀌며, 기존 기록의 등급도 새 기준으로 다시 표시됩니다.

### 3.2.1 — 2026-09-04

3.2.1
• Refreshed the Premium Pass screen icon and plan labels. (Monthly → 1 month)
• Removed the wrong-answer PDF export. You can still review wrong answers in the app with "Retry".

### 3.2.0 — 2026-09-01

구독이 하나로 통합됐어요. 
이제 '프리미엄 이용권' 하나로 비교훈련과 기출훈련을 모두 이용할 수 있습니다.

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## More apps by JinWook You

- [피즐](https://appshunter.io/ios/app/id6752466782)
- [신성우의영점잡기](https://appshunter.io/ios/app/id6793049028)
- [이지은의법갈피](https://appshunter.io/ios/app/id6813027557)

All apps by JinWook You: https://appshunter.io/developer/1837824846

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-13.*