What is the sum of first 14 natural numbers?

A rational number between $${3\over4} $$ and $${3\over8} $$ is :

The difference between the greatest and least five-digit numbers formed by the digits 2,5,0,6,8 is (repetition of digits are not allowed) 

The mean of the first 7 prime numbers is:

The sum of two digit number is 16. If the digit is interchanged the number is formed 18 less than the original number. Find the original number.

The sum of three consecutive numbers is 87. The middle number is : 

The greatest 4-digit number which is a perfect square is

Two numbers are respectively 30% and 40% less than a third number. What percent is the first number of the second?