The number A is the reciprocal of the number B, and the number B is expanded to 10 times the original number to be 50. What is the number A?
甲数是乙数的倒数，乙数扩大到原来的10倍后是50，甲数是多少．
<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>