2. The denominator is 2n- 1, where n is odd positive and n is even negative.

So the number 199 is1(199 * 2-1) =1/397.

3. Every two numbers are a group, in which the first number of each group is a natural number starting from 2 and the last number is-1.

199/2 = 99 ... 1, so the number 199 is the number of 100, so it is 1 00+1=/kloc-.

4.12112112 is a cycle with six negative numbers.

2008/9=223…… 1,

So the number * * in 2008 has 223*6+ 1= 1339 negative numbers.