7 people stand side by side in a row. If A and B must stand at both ends, how many ways can they be arranged?
7个人并排站成一排，如果甲、乙两人必须站在两端，有多少种排法．
<gadget id="calculator">5 * 4 * 3 * 2 * 1 * 2</gadget>
<output>240</output>

<result>240</result>