Verbal Reasoning - Mental Ability Questions

Unit digit of this expression is always 1 as the base ends with 1. 

For the tenth place digit we need to multiply the digit in the tenth place of the base and unit digit of the power and take its unit digit.

i.e, tenth place digit in 2151 is 5 and

tenth place digit in power 415 is 1

And the units digit in the product of 5 x 1 = 5

Therefore, last two digits of 2151415 is 51.

Letters in the word                     Letters in the alphabet

$$\begin{gathered} PRES \\ - - \end{gathered}$$

                                $$\begin{gathered} PQRS \\ - - \end{gathered}$$

$$\begin{gathered} RESEN \\ - - \end{gathered}$$                             $$\begin{gathered} RQPON \\ - - \end{gathered}$$

8th letter of the left of 14th letter from the right means (8 + 14 =) 22nd letter from the right. 22nd letter from the right means (26 - 22 + 1 =) 5th letter from the left.  We know that 5th letter falls into the first half of the series which is reversed.

Hence, the required letter is (13 - 5 + 1 =) 9th letter from the left of the English alphabet.