Students are asked to identify the effect of changing two digits on the value of a number. This multiple-choice question is a "medium hard" test item used in grade 12 in the 2005 National Assessment of Educational Progress (see About NAEP). The URL link (above) takes the user to the NAEP test item, with access to performance data by various subgroups of students, a scoring key, and discussion of the content on which the item is based. The NAEP website allows users to build their own printable database of test items by clicking on Add Question in the upper right hand corner of the screen. NAEP Reference Number: 2005-12M4, No. 9. (sw)