Free
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About
This app offers timed training for mental arithmetic and estimation skills. It includes various arithmetic operations, comparison challenges, and graded sessions to improve your calculation speed and accuracy. Unlock full features with a premium subscription.
✓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
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What's New in Calculation Training
4.0.1
October 16, 2026
• Fixed long fractions in Past Exams being cut off at the screen edges. They now shrink to fit, and wrap onto another line if still too long. • Fractions no longer show grouping parentheses, just the numbers. • Answer with an external keyboard: digits, Backspace and Esc for arithmetic; the greater-than/less-than keys or the arrow keys to pick the larger side in Comparison and Past Exams.
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Subscriptions & In-App Purchases
Premium Monthly
Unlocks Comparison and Past Exam Training
$2.991 Month
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FAQ
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.
