It is known that the average of nine numbers is 72. After removing one number, the average of the remaining numbers is 75. What is the removed number?
已知九个数的平均数为72，去掉一个数后，余下的数平均为75，去掉的数是多少．
<gadget id="calculator">9 * 72</gadget>
<output>648</output>

<gadget id="calculator">8 * 75</gadget>
<output>600</output>

<gadget id="calculator">648 - 600</gadget>
<output>48</output>

<result>48</result>