When a certain number is multiplied by $7$,the product consists entirely of fives; find the least value of such a number.

$(6990 \div 15) \times (468 \div 18) = ?$

$A$ number,when divided by $729$,leaves a remainder of $56$. What will be the remainder if the same number is divided by $27$?

On dividing a number by $56$,we get $29$ as remainder. On dividing the same number by $8$,what will be the remainder?

If the sum of two numbers,one of which is $\frac{2}{5}$ times the other,is $50,$ then the numbers are

The numerator of a fraction is the product of two numbers. One of the numbers is greater than the other by $2$. The greater number is smaller than the denominator $D = 7+c$ (where $c > -7$ is a constant). If the fraction is $f(x) = \frac{(x-2)x}{x+k}$ (where $x$ is the greater number),find the minimum value of the fraction.