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?

Following questions are based on the five three-digit numbers given.
$513, 248, 371, 634, 167$
If the positions of the first and the second digits in each of these numbers are interchanged,which of the following will be the lowest number among them?

Fill in the blank space for the given series with the correct alternative.
$66, 36, 18, (\ldots)$

Find the missing term in the series: $2, 6, 12, 20, 30, ?$

Which term comes next in the sequence: $nd, iy, dt, yo, tj, ?$

Find the missing letters for the given series from the given alternatives:
$aaa....bb....aab.....baaa....bb$