What letters will fill the blank?

Z, X, V, T, R, __,__

Here 2nd number = (1st number x 1 )+1

 3rd number = (2nd number x 2 +2) 

4th number = (3rd number x 3 )+3 and so on..

Therefore, 5th number = (4th number x 4) +4 =57 x 4 + 4 =232.

In the given series,

 2nd term = 1st term -82 = 888-82=440  

 3rd term = 2nd term -82=440-82=216  

and so on...

Here 6th term = 5th term -82=48-82=20

 Therefore, 22 is wrong.

In the given series

1st term has odd number starting from 11, So the Series is 11, 13, 15, 17, 19 

2nd term has an alphabet follwed by its alpha numeric number in the order +4, +3, +2, +1. So  the Series is M13, Q17, T20, V22, W23

Therefore, 15T20 is the answer.

$$\begin{gathered} 63+6=222 \\ \end{gathered}$$ 

Similarly , 253+25=15650

Take a Look at this series :

23 - 22 =  8 - 4 = 4  

33 - 32 = 27 - 9 = 18 

43 - 42 = 64 - 16 = 48  

53 - 52 = 125 - 25 = 100  

63 - 62 = 216 - 36 = 180 

73 - 72 = 343 - 49 = 294 

83 - 82 = 512 - 64 = 448

Fiest series : 3, 5, 7, 9

Second series : 5, 19, 41, ?

 Difference of Second series are 14, 22, 30 etc

Next term is 41+30 i.e equal to 71

Take a Look at the below sereies

2×1+12=3

3×2+22=10

10×3+32=39

39×4+42=172

172×5+52=885

Take a look at the below sereies :

1500 - 25 = 1475

1475 - 27 = 1448

1448 - 29 = 1419

1419 - 31 = 1388

1388 - 33 = 1355

1355 - 35 = 1320

It clearly shows 1389 is Wrong Number