There are 200 students in the sixth grade, 45% of whom are boys. How many boys are there?
六年级有学生200人，男生占45%，男生有多少人？
<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">200 * (9/20)</gadget>
<output>90</output>

<result>90</result>