In an oral calculation competition, Xiao Ming completed 80 questions in 5 minutes and answered 2 questions incorrectly. What is the correct rate of his oral calculations?
在一次口算比赛，小明5分钟完成80道，答错了2道题，他口计算的正确率是多少．
<gadget id="calculator">80 - 2</gadget>
<output>78</output>

<gadget id="calculator">78 / 80</gadget>
<output>39/40 = around 0.975</output>

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

<gadget id="calculator">(39/40) * 1</gadget>
<output>39/40 = around 0.975</output>

<result>39/40 = around 0.975</result>