A residential building ordered 5 copies of the annual "Beijing Evening News" for 900 yuan. Later, some residents ordered three copies of the "Beijing Evening News". How much did these households have to pay?
某居民楼订了5份全年额《北京晚报》用了900元．后来又有居民订了3份《北京晚报》，这几户居民要付多少元？
<gadget id="calculator">900 / 5</gadget>
<output>180</output>

<gadget id="calculator">180 * 3</gadget>
<output>540</output>

<gadget id="calculator">540 + 900</gadget>
<output>1_440</output>

<result>1_440</result>