Given the following fractions: (1/2), (3/4), (9/8), (27/16), ..., then what is the fifth number according to this rule.
已知下列分数：(1/2)、(3/4)、(9/8)、(27/16)，…，则按此规律第5个数是多少．
<gadget id="calculator">27 * 3</gadget>
<output>81</output>

<gadget id="calculator">16 * 2</gadget>
<output>32</output>

<gadget id="calculator">81 / 32</gadget>
<output>81/32 = around 2.53125</output>

<result>81/32 = around 2.53125</result>