HOW TO PLAY

Four numbers. One target. Three chances.

Build your expression

Use each of the four number tiles exactly once to reach the target. You may use +, −, ×, ÷ and parentheses. You cannot join digits together or use unary minus. Intermediate values may be negative or fractional. Division by zero is not allowed.

An example

With 6, 3, 4 and 2, you can reach 24: (6 × 3) + (4 + 2) = 24. The usual order of operations applies. You can undo a tile or clear the expression before submitting.

Chances and hints

You have one official session each day. Three valid wrong answers end it. Missing numbers, syntax mistakes and division by zero never cost a chance. You may use up to two hints: the final operation, then an intermediate step in one solution.

Scoring

A correct answer on your first, second or third submission earns 600, 450 or 300 accuracy points. Zero, one or two hints add 250, 125 or 0 points. Solve within 60 seconds for 150 time points. Each started second after that removes one time point, reaching zero at 210 seconds. Time keeps running while the tab is closed or inactive.

Grades: S ≥ 900, A ≥ 750, B ≥ 550, C ≥ 350, and D for other successful results. A failed or expired challenge scores 0 with grade X.

When does the daily puzzle reset?

A new puzzle opens at 15:00 UTC, which is midnight in Korea. The board shows a countdown and your local reset time. If you start before the reset, you may finish the previous puzzle before 15:10 UTC; it expires exactly at 15:10. A new day has its own session.

Does changing language reset my progress?

No. English and Korean share the same puzzle, timer, hints and attempts in this browser. Refreshing restores your progress. Clearing browser data removes it; records do not sync across devices. Practice is unlimited and does not affect your daily record.

Share without spoilers

Your shared result includes your grade, score, time and hints, but never your expression. Challenge a friend to crack the same daily code.