Calculation: 53-50+47-44+41-38...-14+11-8+5-2=how much.
计算：53-50+47-44+41-38…-14+11-8+5-2=多少．
<gadget id="calculator">53 - 50</gadget>
<output>3</output>

<gadget id="calculator">47 - 44</gadget>
<output>3</output>

<gadget id="calculator">41 - 38</gadget>
<output>3</output>

<gadget id="calculator">3 + 3 + 3</gadget>
<output>9</output>

<gadget id="calculator">3 * 9</gadget>
<output>27</output>

<result>27</result>