Brain Games Installation $ npm install rs-brain-game Run games $ brain-even $ brain-calc $ brain-gcd $ brain-progression $ brain-prime Example 1. Brain-even game. Even/odd number. 2. Brain-calc game. The result of the expression. 3. Brain-gcd game. The greatest common divisor. 4. Brain-progression game. The missing number in Arithmetic Progression. 5. Brain-prime game. Prime number.