title: Ruby coding: Sequence of number pairs "x,y" such that x ranges from 0 to 3 and y from 5 to 7
body: <p>I am stuck on this problem. I tried to solve it with Ruby.</p>
  
  <p>My answer is </p>
  
  <pre><code>4.times{|i| puts "#{i}"} &amp;&amp; 5.upon(7){|i| puts "#{i}}
  </code></pre>
  
  <p>but, I am not sure that it is correct or not.</p>