JavaScript - Clasificar números introducidos en tres grupos

Introduce un número (1-100):<input type="text" id="txtNum" />

<button id="cmdProcess">Clasificar</button>

<table border="1">

	<tr>

		<td>Menores de 30</td> <td>Entre 30 y 70</td> <td>Mayores de 70</td>

	</tr>

	<tr>

		<td id="men30"></td> <td id="men70"></td> <td id="may70"></td>

	</tr>

</table>

<script>

	document.getElementById('cmdProcess').addEventListener('click',function(){

		nNum = document.getElementById('txtNum').value;

		switch (true){

			case (nNum>0 && nNum<=30 ):

				document.getElementById('men30').innerHTML += `${nNum}<br />`;

				break;

			case (nNum>30 && nNum<=70 ):

				document.getElementById('men70').innerHTML += `${nNum}<br />`;

				break;

			case (nNum>70 && nNum<=100):

				document.getElementById('may70').innerHTML += `${nNum}<br />`;

				break;

		}

		document.getElementById('txtNum').value='';

		document.getElementById('txtNum').focus();

	});

</script>