For a finite sequence of nonzero numbers, the number of variations in sign is definded as the number of pairs of consecutive terms of  the sequence for which the product of the 2 consecutive terms is negative.

what is the number of variation in sign for the sequence 1, -3, 2, 5, -4, -6.

请问这个题目的确切含意和解题思路？

答案是3。

题目意思是：对于一个数列来说，“the-number-of-variations-in-sign”定义为数列中积为负数的相邻两项的个数。

对于所给数列，这样的相邻两项有：一二两项，二三两项，四五两项。

基本上是道语文题，题目理解了也就很容易了。