When the little sloppy subtracted a two-digit decimal from 42.6 using the vertical formula, he mistakenly aligned the end of the decimal, and the result was 23.9. What is the correct result?
小马虎在用竖式计算42.6减去一个两位小数时，误将小数的末尾对齐，结果得23.9，正确的结果是多少．
<gadget id="calculator">42.6 - 23.9</gadget>
<output>18.7</output>

<gadget id="calculator">18.7 / 10</gadget>
<output>1.87</output>

<gadget id="calculator">42.6 - 1.87</gadget>
<output>40.73</output>

<result>40.73</result>