Put your query in the adress bar, after the ?q=. Example: https://perguto.github.io/eval-query/?q=2*3 will return 6.
You can also add the site as a search engine to Chrome, Brave, Opera or Vivaldi by going to
chrome://settings/searchEngines, clicking on the Add button next to Site Search and entering https://perguto.github.io/eval-query/?q=%s as the URL
