Notification Number Range

Hi Experts

I had created number range for Notification Types suppose

M1 : 1 to 10000( internal number range)

when i create notification for my 1st notification i am getting number 1 but for my second notification i am getting 10 number,

I am unable to understand where the numbers 2-8 had gone,I am facing problem for m2 and m3 type also please give me solution

Thanks

Susmitha