The page numbers of a certain book are consecutive natural numbers 1, 2, 3, 4, ..., 9, 10, ... When adding these page numbers, someone misses a certain page number, and the result sum is 2001, then the missed page number is How many.
某书的页码是连续的自然数1，2，3，4，…，9，10，…当将这些页码相加时，某人漏计某个页码，结果和为2001，则漏计的页码是多少．
<gadget id="calculator">2_016 - 2_001</gadget>
<output>15</output>

<result>15</result>