During the "June 1st" Children's Day, all children's books in a bookstore will be sold at a 40% discount. During the discount period, the price of a children's book is 5.4 yuan, how much cheaper than the original price?
"六•一"儿童节期间，某书店的儿童读物一律打六折出售．打折期间一本儿童读物的售价是5.4元，比原价便宜了多少元？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5.4 / (3/5)</gadget>
<output>9</output>

<gadget id="calculator">9 - 5.4</gadget>
<output>3.6</output>

<result>3.6</result>