There are 213 small chickens in the chicken farm, and the number of big chickens is twice that of small chickens. How many chickens are there in total?
养鸡场养了213只小鸡，养的大鸡的只数是小鸡的2倍，养鸡场一共养了多少只鸡？
<gadget id="calculator">213 * 2</gadget>
<output>426</output>

<gadget id="calculator">426 + 213</gadget>
<output>639</output>

<result>639</result>