The school organized students to participate in tree planting activities. 113 students went to the fourth grade, 272 students went to the fifth grade, and 287 students went to the sixth grade. How many people go to the three grades?
学校组织学生参加植树活动，四年级去113人，五年级去272人，六年级去287人．三个年级一共去多少人？
<gadget id="calculator">113 + 272 + 287</gadget>
<output>672</output>

<result>672</result>