threads.rb

def random_sum
  Thread.current[:output] = ""
  10.times do
    a = Random.rand(1..1000)
    b = Random.rand(1..1000)
    Thread.current[:output] += "#{a} + #{b} = #{a + b}\n"
  end
  sleep 3
end

def fact(n)
  n == 0 ? 1 : n*fact(n-1)
end

def random_fact
  Thread.current[:output] = ""
  10.times do
    x = Random.rand(5..10)
    Thread.current[:output] += "#{x}! = #{fact(x)}\n"
  end
  sleep 3
end

t1 = Thread.new { random_sum }
t2 = Thread.new { random_fact }
t1.join
t2.join
puts t1[:output]
puts '==='
puts t2[:output]