I have found one bug in custom numeric field. It does not save any value after decimal.
1. Go to custom fields for any module say news or events.( Same applies to field added by code to content block)
2. Add custom numeric field, precision 2 digits after decimal.
3. Create new news/event, set numeric value, in the edit screen it will accept any numeric value even more than 2 digits after decimal point. but in database it will only save the whole number. also for any precision say 1 point or 2 point, in database it will always be set as (decimal(20,0), null)