Use 1, 2, 3, 4, 5 and +, -, *, / to form a calculation formula (without brackets), what is the maximum calculation result.
用1，2，3，4，5和+，-，*，/组合成一个算式(不使用括号)，计算结果最大是多少．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 - (1/2)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">20 + (5/2)</gadget>
<output>45/2 = around 22.5</output>

<result>45/2 = around 22.5</result>