Calculate with a simple method: (3/2)-(5/6)+(7/12)-(9/20)+(11/30)-(13/42).
用简便方法计算：(3/2)-(5/6)+(7/12)-(9/20)+(11/30)-(13/42)．
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 * 2</gadget>
<output>2</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">(3/2) - (5/6)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(7/12) - (9/20)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">5 + 6</gadget>
<output>11</output>

<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">11 / 30</gadget>
<output>11/30 = around 0.366667</output>

<gadget id="calculator">6 + 7</gadget>
<output>13</output>

<gadget id="calculator">6 * 7</gadget>
<output>42</output>

<gadget id="calculator">13 / 42</gadget>
<output>13/42 = around 0.309524</output>

<gadget id="calculator">(11/30) - (13/42)</gadget>
<output>2/35 = around 0.057143</output>

<gadget id="calculator">(2/3) + (2/15) + (2/35)</gadget>
<output>6/7 = around 0.857143</output>

<result>6/7 = around 0.857143</result>