What is the reciprocal of the sum of all the simplest proper fractions whose fraction unit is (1/9).
分数单位是(1/9)的所有最简真分数的和的倒数是多少．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>