87+88+89+90+91+92+93=how much.
87+88+89+90+91+92+93=多少．
<gadget id="calculator">90 * 7</gadget>
<output>630</output>

<gadget id="calculator">(-3) - 2 - 1</gadget>
<output>-6</output>

<gadget id="calculator">(-6) + 1 + 2 + 3</gadget>
<output>0</output>

<gadget id="calculator">630 + 0</gadget>
<output>630</output>

<result>630</result>