Which of the following will be the middle digit of the second lowest number among the five numbers given below?
$317, 528, 439, 254, 861$

If $2$ is subtracted from each odd digit and $3$ is added to each even digit in the number $3675249$,how many digits will appear twice in the new number thus formed?

Fill in the blank space for the given series with the correct alternative.
$2, 6, 12, 20, 30, 42, 56, (\dots)$

To answer these questions study carefully the following arrangement of letters, digits and symbols.

$6,=,\$, C,E, 3,8 ,G,L,M, 7, \star, @ ,P,R, 4, \# ,N,T, 5, S,V$

If all the symbols in the arrangement are removed, then which of the following will be the $7^{th}$ to the left of the $13^{th}$ element from the left end?

Second and third digits of each number given below are interchanged. Then,the $1st$ and the last digits of each new number thus formed are interchanged. Which of the following numbers then will be the highest number among the five?
$273, 372, 438, 184, 526$

Fill in the blank space for the given series with the correct alternative.
In the series $3, 9, 15, . . .$ what will be the $21^{st}$ term?