After Xiao Ming finished his homework, he checked it again and found that 18 questions were correct and 2 questions were wrong. What is Xiao Ming's correct rate for this homework?
小明写完作业后检查了一遍，发现有18道题正确，2道题错误，这次作业小明的正确率是多少？
<gadget id="calculator">18 + 2</gadget>
<output>20</output>

<gadget id="calculator">18 / 20</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(9/10) * 1</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>