□/9=20…□, to maximize the remainder, what should the dividend be equal to.
□/9=20…□，要使余数最大，被除数应该等于多少．
<gadget id="calculator">20 * 9</gadget>
<output>180</output>

<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">180 + 8</gadget>
<output>188</output>

<result>188</result>