title: Error when importing mathematics in Unity3d
body: <p>When I try to import mathematics it throws me an error saying that</p>
  <p><strong>'' error CS0234: The type or namespace name 'Mathematics' does not exist in the namespace 'Unity' (are you missing an assembly reference?)''</strong></p>
  <p>I tried, <strong>Using System.Mathematics</strong>, <strong>Using Unity.Mathematics</strong> I also tried by typing Math instead of Mathematics. Idk why this is throwing an error,
  I use Notepad++ for scripting.</p>
  <p>[1]: <a href="https://i.stack.imgur.com/vNs9J.png" rel="nofollow noreferrer">https://i.stack.imgur.com/vNs9J.png</a> &lt;--- Error picture</p>