The school bought 30 packs of exercise books, 20 books in each pack, and each book was 0.3 yuan. How much does it cost to buy these exercise books?
学校买来30包练习本，每包20本，每本0.3元．买这些练习本要多少元？
<gadget id="calculator">0.3 * 20 * 30</gadget>
<output>180</output>

<result>180</result>