A CHALLENGE FOR YOUR EYE
Cut to the Mark
Move the line. Make the left piece match the target.
Pick a mode and begin
5 rounds, about 1–2 minutes. Take your time—there’s no time limit.
The target is 50% each round.
You have a game in progress
Make left A50%
Match its share of the whole shape’s area.
Trust your eye.
We’ll reveal the actual percentage after your cut.
Five cuts. Challenge complete!
How close did you get?
A new personal best!
Your five cuts
| Round | Target | Left piece | Error | Points |
|---|
Your score follows this game’s scoring rules.
Try a different target.
25%, 40%, 50%, 60%, 75%. A new target changes the way you see it.
How is the score calculated?
Error is the difference between the actual left area and the target, in percentage points (pp). Round score = round(max(0, 100 − 4 × error)). Add five integer round scores for a maximum of 500. A 55% cut at a 50% target has 5 pp error and earns 80 points. Display values use one decimal place; calculations use full precision. There is no speed bonus.
Frequently asked questions
How is area measured?
We calculate the actual polygon area. Half the width does not always mean half the area.
Can I see the answer first?
Actual percentages and the target line appear only after you confirm. Confirmed cuts cannot be changed.
Where are records kept?
Your latest completed game and best game per mode are stored in this browser. There are no accounts or device sync. Clearing site data removes the records.
Can I switch languages mid-game?
Switch between Korean and English in the same tab to keep your shapes and progress. This may not work if browser storage is blocked.
Does the copied link repeat these shapes?
New results include a link to the same shapes and targets. Older results without reproducible challenge information use the standard game address. Result images do not verify scores.