Define number ranges for Material Type

Dear Friends,

Can any one tell me how to Define and assign the number range for Material type

I have a scnario that

My FG Materials should have Number rage as 3000001 to 3999999

My RM should have number range As 1000001 to 1999999

My Trading Materials Should Have Number range as 4000001 to 4000009

please tell me the procedure for the same

Regards

Shakthi