What is the numerator of the denominator (5) of the prime factorization of $6/30$

Question

I am simplifying the fraction $6/30$ which I know is $1/5$.

It's pretty self-explanatory.

However, when I use prime factorization to simplify it, I am left with a denominator of $5$ with nothing above.

$6/30$ :

$6 = 2 \cdot 3$
$30 = 2 \cdot 3 \cdot 5$

$2$ and $3$ cancel each other out.

You are left with $5$ as the denominator with nothing above as the numerator. What above it makes it $1/5 = 20\% = 20/100$.

Answer 1

You forgot that

$$6=3\times2\times1$$

You always have a $1$ in this cases.

Answer 2

$1$ has the key property that $1×n=n$ for all $n$, just as $0$ has the key property that $0+n=n$. When you add no numbers, you get $0$. When you multiply no numbers, you are left with $1$