When a positive integer n is divided by 5 the remainder is 2. What is the remainder when the number 3n is is divided by 5 ?

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

What is the sum of two consecutive even numbers, the difference of whose square is 84? 

In a school $${1\over10} $$ of the boys are same in number as $${1\over4}$$ of the girls and  $${5\over8} $$ of the girls are same in number as $${1\over4}$$   of the boys. The ratio of the boys to girls in that school is: 

Find the least number which when divided by 12, 15, 18 and 27 leaves remainders 10, 13, 16 and 25 respectively.

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

In a two digit number if it is known that its unit digit exceeds its tens digit by 2 and that the product of the given number and the sum of its digits is equal to 144, then the number is 

The mean of the first 7 prime numbers is: