When we have items that have decimal values with several digits, the crawled value seems to be changed. For example, when we expect 1234567.89, we get 1234567.875 in the result of search. This affects the advanced search using this specific crawled property.
This is a known issue in SharePoint 2007.
The SharePoint Search 2007 engine internally stores certain values obtained during the crawl as floating point numbers. When the number obtained is sufficiently large (> 7 places), there is an inherent loss of precision in the conversion to floating point number stored in the metadata index. SharePoint Search 2010 took a design change to acquire, store, and retrieve this type of value in a different internal structure that did not cause this loss of precision.