Okay, aforementioned was the problem:

We need to count all the positive integers with at least two consecutive ones.
The way I thought about it was:

There are $10^{5}$ ways to have numbers that are less than 100 000. Now from these, I need to subtract the number of numbers which have either no consecutive ones or one pair of consecutive ones. And we can do that by saying:

Number of no consecutive ones: ....

But this doesn't work. How to think about the problem in a easy way?Can someone help?