Blink if Prime

Inspired by Breathe if Prime by Cary Huang (@carykh)

What is Blink if Prime?

Blink if Prime is a simple game: a counter increases by 1 every second. Your task is to blink (yes, I tried to detect breathes...) exactly when the current number is prime. Any mistake ends the game immediately.

Rules are strict: blinking on a composite number ends the game, but not to blink on a prime doesn't end the game. The goal is to reach the highest number possible.

How to Play

  1. Conuter: A number at the center of the screen increases by 1 every second.
  2. Identify primes: Only numbers divisible by 1 and themselves are prime. Examples: 2, 3, 5, 7...
  3. Blink: Blink exactly when a prime appears.

Strategies

1. Learn Early Primes

Memorize primes under 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

2. Use Divisibility Rules

  • Even numbers >2 are not prime.
  • Numbers ending in 5 >5 are not prime.
  • Numbers where the sum of digits is divisible by 3 are not prime.

3. Prime Gaps

As numbers increase, primes appear less frequently. Be ready to wait without blinking during long sequences of non-primes.

4. Check for Composite Traps

Some numbers look prime but aren’t, e.g., 51 (3×17), 57 (3×19), 91 (7×13).