method

prime?

Ruby latest stable (v2_5_5) - 0 notes - Class: Integer

1_8_6_287
1_8_7_72
1_8_7_330
1_9_1_378 (0)
1_9_2_180 (0)
1_9_3_125 (0)
1_9_3_392 (0)
2_1_10 (0)
2_2_9 (-38)
2_4_6 (0)
2_5_5 (0)
2_6_3 (0)
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prime?() public

Returns true if self is a prime number, else returns false.

# File lib/prime.rb, line 34
  def prime?
    return self >= 2 if self <= 3
    return true if self == 5
    return false unless 30.gcd(self) == 1
    (7..Integer.sqrt(self)).step(30) do |p|
      return false if
        self%(p)    == 0 || self%(p+4)  == 0 || self%(p+6)  == 0 || self%(p+10) == 0 ||
        self%(p+12) == 0 || self%(p+16) == 0 || self%(p+22) == 0 || self%(p+24) == 0
    end
    true
  end

prime?

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