Xiao Ming's mother bought her 10 math exercise books, 20 Chinese exercise books, and 5 300-word pickaxe papers. If she takes any one of them, what is the probability of getting the math exercise book?
小明的妈妈给她买了10本数学练习本，20本语文练习本，5本300字镐纸，从中任意拿一本，拿到数学练习本的可能性是多少．
<gadget id="calculator">10 + 20 + 5</gadget>
<output>35</output>

<gadget id="calculator">10 / 35</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>