percent troubles

Students who can work with fractions and decimals still have an inordinate amount of trouble with percents. They can answer the questions, “What decimal is 3/4?” and, “What percent is .75?” and yet not be able to write 3/4 as a percent. They can know that .2=20%. They can work with the problem, “80% of what number is 40?” and can know that 100-20=80 and yet not have any idea of how to solve the problem, “Jackson paid $40 for a jacket which was on sale for 20% off. What was the regular price of the jacket?” (How many students would solve that problem by taking 20% of $0=$8, and concluding erroneously that the regular price must be $0+$8=$48?!)

Math Word Problems Decimals & Percents Level B, p. iv
by Anita Harnadek
ISBN 0-89455-821-8

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