index.html

<!DOCTYPE html>
<html>
<body>

  <h1>The input element</h1>
  
  <form>
   <label>Enter Temperature in celsius: </label>
   <input type="text" id="tempC">
   <button type="button" onclick="tempInFar()">Check</button>
   <p>Temp in Farenheit: <span id="tempCF"></span> F
   </p>
   
   <label>Enter Temperature in farenheit: </label>
   <input type="text" id="tempF">
   <button type="button" onclick="tempInCel()">Check</button>
   <p>Temp in Celcius: <span id="tempFC"></span> C
   </p>
  </form>
  
  <form>
  <label>First number:</label>
  <input type="text" id="fnum"><br><br>
  <label>Last number:</label>
  <input type="text" id="lnum"><br><br>
  <button type="button" onclick="multiply()">Multiply</button>
  <button type="button" onclick="divide()">Divide</button>
  <p>The result is: <span id="pname"></span>
  </p>
  </form>
</body>
</html>