How many numbers less than $100$ have exactly four factors? 

Two odd numbers have 36 factors each and the HCF of these two numbers is $225$. What is the minimum possible LCM of these two numbers if the power of any prime factor $1$ in these two numbers is not more than $3$?

Find the remainder when ${\left[{\left(7!\right)}^{6!}\right]}^{17777}$ is divided by $17$?

$X$ is a number formed by writing the first $1002$ whole numbers one after another from left to right then a vertical line is drawn which divides the number such that the number of digits on either side of line is the same. Find the remainder when the number formed by the digits on the left of the vertical line, is divided by $625$. 

Amongst all the four digit natural numbers divisible by $24$, how many have the number $24$ in them? 

If $X$ is a natural number & $X < 100$ then the number of values of $X$ for which $18X + 2$ & $12X + 1$ are relatively prime?