There was 23.42 yuan in Xiaohua's piggy bank, but yesterday he spent 4.5 yuan to buy a pen, and today his mother gave him another 40 cents, how much money is in Xiaohua's piggy bank now?
小华的储钱罐里原有23.42元，昨天他买钢笔用去了4.5元，今天妈妈又给了他4角5分，小华的储钱罐里现在有多少钱？
<gadget id="calculator">23.42 - 4.5</gadget>
<output>18.92</output>

<gadget id="calculator">18.92 + 0.45</gadget>
<output>19.37</output>

<result>19.37</result>