In a batch of parts, 225 parts are tested as first-class products, and the remaining 25 parts are second-class products. What is the rate of first-class products?
一批零件，经检验225个是一级品，其余25个是二级品，一级品率是多少．
<gadget id="calculator">225 + 25</gadget>
<output>250</output>

<gadget id="calculator">225 / 250</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>