The Little Math Puzzle Contest: Puzzles #6 to 10

----------------------------------------------------------------
Puzzle #6 :

What are the next 2 numbers?.... 3,  1,  4,  1,  5,  9, ___, ___

----------------------------------------------------------------
Puzzle #7

What is the next letter in the set?.... R, E, B, M, U, ___

----------------------------------------------------------------
Puzzle #8

What are the next two integers? 
       21,  20,  18,  15,  11,  6,  __,  __  

----------------------------------------------------------------
Puzzle #9

What are the next two integers?   2, 3, 5, 7, 11,  __ ,  __  

----------------------------------------------------------------
Puzzle #10

What are the next three letters?  B, C, D, F, G, H, J, K, L, M, __ ,  __  ,  __