The least number to be subtracted from $16800$ to make it a perfect square is

Twenty-one times a positive number is less than its square by $100$. The value of the positive number is:

If $x+\frac{2}{3+\frac{4}{5+\frac{7}{6}}}=10$,then the value of $x$ is

If $x+y+z=1, xy+yz+zx=-1, xyz=-1,$ then $x^{3}+y^{3}+z^{3}$ is

$A$ person was to multiply a fraction by $\frac{6}{7}$. Instead,he divided the fraction by $\frac{6}{7}$ and got an answer which exceeds the correct answer by $\frac{1}{7}$. The correct answer is:

What is the value of the positive square root of $(69 + 28 \sqrt{5})$?