The number of results displayed next to the search facets/filters does not always match the number of search results when searching on WorldCat.org. This discrepancy is due to the way search results are clustered. The search facets show flat search results, meaning each record containing that facet is counted once. Search results are clustered so that titles with multiple records for different formats and editions are grouped under one result. You can see all the records that are clustered under one search result by clicking the View All Formats and Editions link.