Xiaodong reads a 420-page book, and he reads 26 pages a day. After 13 days of reading, how many pages are left?
小东看一本420页的书，他每天看26页，看了13天后，还剩多少页没看？
<gadget id="calculator">26 * 13</gadget>
<output>338</output>

<gadget id="calculator">420 - 338</gadget>
<output>82</output>

<result>82</result>