Use this definition: A prime number is a positive whole number with no factors other than itself and 1. For example, $2,13,$ and 37 are primes, but 24 and 39 are not. By convention 1 is not considered prime, so the list of the first few primes is as follows:
Let $f$ be the function that assigns to each natural number $X$ the number of primes that are less than or equal to $x$. For example, $f(12)=5$ because, as you can easily check, five primes are less than or equal to $12 .$ Similarly, $f(3)=2$ because two primes are less than or equal to $3 .$ Find $f(8)$ $f(10),$ and $f(50)$.