Ruby の学習 次の数字列から連続する4桁の数字を取り出したとき、3の倍数はいくつあるか

VMware Fusion for Mac | Fusion 入門

#!/usr/bin/ruby
number_sorce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
result = 0 
first = 0 
ends = 3 
  
until ends > number_sorce.size
  number_4 = number_sorce[first..ends].to_i
  if number_4 % 3 == 0
    result += 1
  end 
  first += 1 ; ends += 1
end
 
puts result