Uncle Wang participated in the rural cooperative medical insurance. The clause stipulates: farmers' inpatient medical expenses compensation deductible line, county-level hospitals are 400 yuan (that is, all within 400 yuan are paid by themselves), and the part above the deductible line is compensated at 90%. This year, Uncle Wang suffered from acute enteritis and was hospitalized in Huaping County People's Hospital for 10 days. The total medical expenses were 3,800 yuan. According to regulations, how much should Uncle Wang pay himself?
王大伯参加了农村合作医疗保险．条款规定：农民住院医疗费补偿起付线，县级医院400元(即400元以内全部自付)，在起付线以上的部分按90%补偿．今年王大伯患急性肠炎在华坪县人民医院住院治疗10天，共计医疗费3800元．按规定王大伯应自付多少元？
<gadget id="calculator">3_800 - 400</gadget>
<output>3_400</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">3_400 * (1/10)</gadget>
<output>340</output>

<gadget id="calculator">340 + 400</gadget>
<output>740</output>

<result>740</result>