How to get the number of decimal places configured for a site column

Hi,

I have a column 'SampleNumCol' of type Number, the number of decimal places to be displayed is configured as 2.
The column conatins a value, but when retrieved programatically is displayed as 5.00000000  instead of 5.00.
I am retrieving this column using listitem.Properties[field.InternalName].

I need to trim the decimals based on  number of decimal places configured for the site column.

How to get the number of decimal places configured for a site column?

Thanks in advance,
dhijit