说明：  1/1 + 1/2 + 1/3 + 1/4 + ... 在数学上称为调和级数。 它是发散的，也就是说，只要加上足够多的项，就可以得到任意大的数字。 但是，它发散的很慢： 前1项和达到 1.0 前4项和才超过 2.0 前83项的和才超过 5.0 那么，请你计算一下，要加多少项，才能使得和达到或超过 15.0 呢？
(1/1 +, 1/2 +, 1/3 +, 1/4 +... Are mathematically called harmonic series. It is divergent, that is, as long as you add enough items, you can get any large number. But it diverges very slowly: The first 1 and reach 1 First 4 and only over 2 The sum of the first 83 is only over 5 Well, please count it. How many items can you add to make it reach or exceed 15?)