The unit price of a fitness ball is 18 yuan/piece. How much is the total cost of purchasing 55 exercise balls in the school sports room?
健身球的单价是18元/个．学校体育室购买55个健身球，一共用去多少元？
<gadget id="calculator">18 * 55</gadget>
<output>990</output>

<result>990</result>