There are 726 students in the fourth, fifth and sixth grades in a certain school, including 225 students in the fourth grade, 15 more students in the fifth grade than the fourth grade, how many students are there in the sixth grade?
某校四、五、六年级共有学生726人，其中四年级有225人，五年级比四年级多15人，六年级有多少人？
<gadget id="calculator">225 + 15</gadget>
<output>240</output>

<gadget id="calculator">726 - 225 - 240</gadget>
<output>261</output>

<result>261</result>