Flash vs Byeoldosa

Train your mental arithmetic with numbers that flash one at a time. Watch the sequence, add it in your head, and enter the total before the next round. Flash keeps practice simple: • Choose 1–7 digits and 2–500 numbers. • Set the display speed from 0.1 to 3.0 seconds. • Practice 1–999 rounds or keep going in Infinite mode. • Turn answer input and automatic continuation on or off. • Choose a light or blue background. • Use sound, haptic, or both for feedback. • Save your favorite settings as presets. • Check accuracy, response time, streaks, and total training time. • Review the exact number sequence for each round and retry mistakes. Use it for a quick session or a longer challenge. Flash gives you a clear way to practice at your own pace.

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.