When a custom field is created and marked searchable for any of the various numeric data types (currency, integer, number, real #) you can only search for these fields with an exact value.

A better method of searching these fields is to set a range of values to find. For example, a school using the Insidesales.com system may have a real # custom field called "GPA." When searching for applicants by GPA it makes more sense to search for a GPA of 3.1 and up rather than just searching for students with a GPA of exactly 3.1. While the latter may be needed at times, the former will often times be much more useful in practical application.