There are 267 boys and 233 girls in the third grade. 398 of them have already visited the museum. How many of them have not?
三年级有男生267人，女生233人，已经参观过博物馆的有398人，还没有参观过的有几人？
<gadget id="calculator">233 - 398</gadget>
<output>-165</output>

<gadget id="calculator">267 + (-165)</gadget>
<output>102</output>

<result>102</result>