For the following questions answer them individually
The value of $$\left(1 - \frac{1}{5}\right)\left(1 - \frac{1}{6}\right)\left(1 - \frac{1}{7}\right) ........ \left(1 - \frac{1}{20}\right) =$$
The rate of simple interest per annum that makes some amount of money double in 12 years is
If a, b, c are real and a + b + c = 0, then $$x^{a^2b^{-1}c^{-1}}.x^{a^{-1}b^{2}c^{-1}}.x^{a^{-1}b^{-1}c^{2}} =$$
$$\sqrt{15 + 2\sqrt{15} + 2\sqrt{21} + 2\sqrt{35}} + \sqrt{15 - 2\sqrt{15} - 2\sqrt{21} + 2\sqrt{35}} =$$
The greatest three digit number which whendivided by 6, 9 and 12 leaves the remainder 4 in each case is