Allow leading zeros in number formatted custom fields

We would like to have number formatted custom fields that allow numbers that start with a zero. Currently, the custom form will save any number entered but will delete the zero from the field once its saved. We are using this form to store codes that often start with a zero and it's important that it stays as-is for our metadata. Reverting to text is not ideal, because we do want it to kick out any attempts to store letters. Can the number formatting be changed to allow leading zeros?