A certain company bought a batch of office supplies, including 78 notebooks at 2.5 yuan each. The money spent on buying pens was 2.5 times that of notebooks. How much did it cost to buy pens?
某公司买了一批办公用品，其中笔记本买了78本，每本2.5元，买钢笔用的钱是买笔记本的2.5倍，买钢笔用了多少元钱？
<gadget id="calculator">78 * 2.5 * 2.5</gadget>
<output>487.5</output>

<result>487.5</result>