The Fry Graph for Estimating Readability (Extended) and George Magginnis' formula for passages shorter than 100 words were used in an investigation of the reading levels of 18 mathematics textbooks produced for grades one through six by three major publishers. The results indicated that the readability levels of the textbooks were inaccurate. Few books were appropriate for the average child and few were for the slow or low-achieving child. None of the third grade books and only one fifth grade book were on level. Two other fifth grade books had seventh grade readability levels. (FL)