How to display a different format for the Number customfield

If you do not like how the Number custom field is displaying in Jira (for example, if you do not want it to display the commas), you can modify a velocity file to configure this. In particular, look at the file WEB-INF/classes/templates/plugins/fields/view/view-number.vm. As mentioned here:

At the moment to change the way the numbers are printed the easiest thing to do is to edit:
WEB-INF/classes/templates/plugins/fields/view/view-number.vm
under the JIRA web application and replace:
$!numberTool.format($value)
with:
$value.longValue()

and restart.