0.8% of a number is 31, then find the number.

The sum of the HCF and LCM of two numbers is 680 and the LCM is 84 times the HCF. If one of the numbers is 56, the other is : 

In a box there are 6 blue ball, X red balls & 10 green balls. Probability of choosing one red ball from the given box is $$ {1\over 3}$$. Then find the sum of red and blue balls in the box?

A sum borrowed under compound interest doubles itself in 10 years. When will it become fourfold of itself at the same rate of interest?

If each interior angle is doubled of each exterior angle of a regular polygon with n sides, then the value of n is 

The length & breadth of a rectangle is in ratio 4 : 7. If perimeter is 88 cm. find area of rectangle.

If $$ {x+{1\over x}=\sqrt{3}}$$ then $$ {x^{48}+x^{378\over7}+x^{726\over11}+x^{60}}$$ is equal to

The product of two consecutive odd numbers is 399. Find the lower of them.