By Celia Baron. 1) Statement 2 is false. 2) Statement 3 is false. 3) Statement 4 is false. 4) Statement 1 is false. How many statements are true? The 81 mental challenges here (one per illustrated reproducible page) can sometimes be problems of pure logic, sometimes mathematical, sometimes visual (responding to a picture), and sometimes spatial. Strategies required: trial and error, finding a pattern, working backward, elimination, estimation, algebra, listing, sketching, and logical thinking. Grades 4–8. Answer key. Illustrated. 90 pages. Second Edition.