If 5*2=11, 6*3=21, 7*4=34, then, 1*9+2*9+3*9+...+9*9=how much.
如果5*2=11，6*3=21，7*4=34，那么，1*9+2*9+3*9+…+9*9=多少．
<gadget id="calculator">45 * 9</gadget>
<output>405</output>

<gadget id="calculator">9 + 72</gadget>
<output>81</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">81 * 4</gadget>
<output>324</output>

<gadget id="calculator">405 + 324</gadget>
<output>729</output>

<result>729</result>