Timer99 vs Byeoldosa
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Timer99
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Timer app that can measure 1 to 999 minutes easily and quickly with only 3 taps. This timer does not have a start button. Just tap the number you want to measure and the timer countdown will start. For example ... -To measure 120 minutes, just press 1,2,0. -To measure 45 minutes, just press 4,5. -Just press 8 to measure 8 minutes.
Byeoldosa
This app offers step-by-step practice for basic arithmetic operations like addition, subtraction, multiplication, and division. It features levels organized by difficulty, from single-digit to three-digit numbers, with a vertical calculation mode that mimics writing sums on paper. Progress is automatically saved and visualized in charts to track speed and accuracy improvements.
- Step-by-step arithmetic practice
- Addition, subtraction, multiplication, division
- Difficulty levels
- Vertical (column) calculation mode
- Automatic practice set saving
- Progress charts for speed and accuracy
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Byeoldosa is an arithmetic practice app for working through addition, subtraction, multiplication, and division step by step. • Levels are organised by difficulty, so you can start from the basics and move on to more advanced problems at your own pace. • Problems range from single-digit to three-digit numbers, with stages that change depending on whether carrying or borrowing is involved. • In vertical (column) calculation mode, you can follow each column one box at a time, much like writing out the sum on paper. • Every practice set is saved automatically, and your scores and time spent are shown in simple charts, so you can see how your speed and accuracy change as you keep practising. It’s a good fit for students who want to strengthen their arithmetic, for anyone who’d like a bit of mental exercise, or for those moments when you just feel like doing a few number problems. Whenever you feel like practising numbers, just open Byeoldosa.
Screenshots
Verdict
The clearest difference is update cadence: Timer99 at every 2 days against Byeoldosa's every 6 months. Timer99 also leads on iOS requirement (13.0 vs 18.0). On price, ads, in-app purchases 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. Neither carries in-app purchases, so what you see is what you pay.
Timer99 ships an update every 2 days, Byeoldosa every 6 months. The most recent releases landed on October 27, 2026 and November 3, 2026 respectively.
| Parameter | Timer99 | Byeoldosa |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (1 ratings) — better |
| Number of ratings | — | 1 — better |
| Update frequency | Every 2 days — better | Every 6 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Free |
| Devices | iPhone, iPod | iPhone, iPad |
| Requires iOS | 13.0 — better | 18.0 |
| Further details — not scored | ||
| Size | 8 MB | 10 MB |
| Age rating | 4+ | 4+ |
| Developer | Takahashi Naoto | Hyekyung Jeong |
In-app purchases
Timer99
No in-app purchases
Byeoldosa
No in-app purchases









