5.101001000100001....

he decimal number aboce consists of only one and 0 to the right of the decimal point. The first is followed by one 0, the second 1 is followed by two 0, the third 1 is followed by three 0 and so on. What is the total number of 0s between the 98th and the 101st 1 in this decimal number?

what i supposed was that 98th 1 has 98 0, and so on, thus i added up 98+99+100=297.... but for some reason the asnwer is 291. I need a good explanation, and some tips to solve number pattern problems and sequence problems. Thank you very much for your help!