If $\Delta$ stands for the operation on adding first number to the twice of the second number. Then, find the value of $(2\ \Delta\ 3)\ \Delta\ 4$.

Which is the greatest among $16\frac{2}{3}\%$, $6\frac{1}{2}\%$, $\frac{2}{17}$ and $0.173$ ?

The sum of an Infinite geometric series is 4 and the sum of the cubes of the terms of the same GP is 192. The common ratio of the original geometric series is:

How many terms are there in the series 201, 208, 215, ....., 369?

What is the value of $\left(1-\frac{1}{n}\right)+\left(1-\frac{2}{n}\right)+\left(1-\frac{3}{n}\right)+\cdots$ upto n terms?

For the Arithmetic Progression : $\frac{3}{2}, \frac{1}{2}, -\frac{1}{2}, -\frac{3}{2}$....the common difference d is :

Find the A.P. whose 3rd term is 18 and 12th term is 72.