title: Function gives NAN instead of a string
body: <p>i'm a beginner in JS and i have a problem with this function:
  first of all i defined it :</p>
  
  <pre><code>function highAndLow(numbers){
       numbers = numbers.replace(/ /g,",");
       let high = Math.max(numbers);
       let min = Math.min(numbers);
       console.log("The max value is "+high+ ", and the minimum is "+min);
  };
  </code></pre>
  
  <p>and when i call it :</p>
  
  <pre><code>console.log(highAndLow("1 2 3 4 5"));
  </code></pre>
  
  <p>i get the following output : </p>
  
  <pre><code>The max value is NaN, and the minimum is NaN
  </code></pre>
  
  <p>So please could you show where is the problem and thanks in advance.</p>