CLASSIFY FAST · 20 TRIALS
See one number. Decide whether it divides evenly by two.
Classify 20 numbers. Mistakes and timeouts count, then the game continues.
READY?
Press E or Left Arrow for EVEN. Press O or Right Arrow for ODD.
Keyboard: E / ← for even · O / → for odd. Touch or mouse: choose a large button.
HOW TO PLAY
Start the game and watch the large number in the center.
Choose EVEN when the number divides by two with no remainder. Otherwise choose ODD.
Finish all 20 standard trials, or keep a perfect streak as the endless timer shrinks.
EVEN ODD REACTION GAME
Every round combines number recognition, a simple parity decision, and a fast two-choice response. The standard game contains exactly ten even and ten odd numbers.
It is a recreational browser challenge, not a diagnostic assessment. Practice, device latency, input method, and attention can all affect your result.
READ YOUR RESULT
Accuracy includes all answers and timeouts. Average and best reaction times use correct answers only.
For a fair personal comparison, repeat the same mode with the same device and input method.
QUESTIONS
A whole number is even when its last digit is 0, 2, 4, 6, or 8. A last digit of 1, 3, 5, 7, or 9 means it is odd.
The answer counts as incorrect and the next number appears. Standard mode always completes exactly 20 trials.
The first deadline is 1.8 seconds. It becomes shorter after correct answers, down to 350 milliseconds. One error or timeout ends the run.
Yes. Tap the two large buttons on mobile, click them with a mouse, or use E and O or the left and right arrow keys.