The library bought 5 sets of "One Hundred Thousand Whys" series, each set cost 280 yuan, how much does it cost in total?
图书室买了5套《十万个为什么》丛书，每套280元，一共需要多少元？
<gadget id="calculator">280 * 5</gadget>
<output>1_400</output>

<result>1_400</result>