Number field when empty and value=0 Is there a way to differentiate the number field value empty and 0? 

I would like to display this field only when there's a value in the field even though the value is 0. 

But when I input 0 into the field, it seems that Craft thinks the value is empty... so doesn't still display the field. 

Thanks.
Twig's is not null should work for this.  Assuming you have a Number field called number and you're looping through a list of entries, something like this should work:

{% for entry in entries if entry.number is not null %}
    {{ entry.number }}
{% endfor %}