Regulations: ②=1*2*3, ③=2*3*4, ④=3*4*5, ⑤=4*5*6, ... if (1/(⑥))-(1/(⑦) )=(1/(⑦))*A． So, what is A?
规定：②=1*2*3，③=2*3*4，④=3*4*5，⑤=4*5*6，…如果(1/(⑥))-(1/(⑦))=(1/(⑦))*A．那么，A是几？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>