Which term of the sequence $( - 8 + 18i),\,( - 6 + 15i),$ $( - 4 + 12i)$ $,......$ is purely imaginary
$5^{th}$
$7^{th}$
$8^{th}$
$6^{th}$
If $a_m$ denotes the mth term of an $A.P.$ then $a_m$ =
Find the sum of all numbers between $200$ and $400$ which are divisible by $7.$
Find the sum of odd integers from $1$ to $2001 .$
The difference between any two consecutive interior angles of a polygon is $5^{\circ}$ If the smallest angle is $120^{\circ},$ find the number of the sides of the polygon.
If twice the $11^{th}$ term of an $A.P.$ is equal to $7$ times of its $21^{st}$ term, then its $25^{th}$ term is equal to