What is the sum of the numbers divisible by 7 between 300 and 400?
300到400之间能被7整除的各数之和是多少？
<gadget id="calculator">7 * 43</gadget>
<output>301</output>

<gadget id="calculator">7 * 57</gadget>
<output>399</output>

<gadget id="calculator">301 + 399</gadget>
<output>700</output>

<gadget id="calculator">57 - 43</gadget>
<output>14</output>

<gadget id="calculator">14 + 1</gadget>
<output>15</output>

<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">700 * (15/2)</gadget>
<output>5_250</output>

<result>5_250</result>