First letter moves 6 steps forward. Second letter moves 6 steps backward.

Clearly, alternatively we add and subtract 10% of a term to obtain the next term of the series.
Thus, 10000 + (10% of 10000)= 11000;
11000 - (10% of 11000) = 9900;
 9900 + (10% of 9900)  = 10890;
10890 - (10% of 10890) = 9801.
 9801 + (10% of 9801)  = 9801+980 = 10781.
So, missing term = 10890- (10% of 10890)= 9801.

The given sequence is a combination of two series:
i)0, 3, 8, 15, 24, 35
ii)2, 5, 10, 18, 26
The pattern in both i, ii is +3, +5, +7, . . . .
So, in ii) 18 is wrong and must be replaced by (10 + 7) = 17

1.)D + 12 = P
P + 12 = B
B + 12 = N
2.)H + 12 = T
T + 12 = F
F + 12 = R
3.)L + 12 = X
X + 12 = J
J + 12 = V

The given series follows a pattern that,

19 x 19 x 19 = 6859

18 x 18 x 18 = 5832

17 x 17 x 17 = 4913

16 x 16 x 16 = 4096

15 x 15 x 15 = 3375

So, the missing number in the given series = 4913  

The correct pattern is -192, -96, -48, -24, -12, -6
So, 48 is wrong and must be replaced by (92 - 48) = 44

In the first step, one letter from the beginning and one from the end of a term are removed to give the next term . In the second step, two letters from the beginning of the term are removed. These two steps are repeated alternatively

Given series follows Cubes on Prime Numbers 

i.e 2 3 , 3 3 , 5 3 , . . .but   9 3is 1331

so 1381 is wrong

The series follows a pattern that,

-9², +8², -7², +6², -5²