What do you prefer,

`1 \times 10^{10}`

or `1E10`

.A "reduced fraction" is a fraction that has the smallest possible integer numerator and denominator for its value.

For example:
is not a reduced fraction, because there is another fraction equal to it but with smaller numerator and denominator:

$63 $

$21 $

en.wikipedia.org/w/index.php?title=Farey_sequence&oldid=1223364653#Sequence_length_and_index_of_a_fraction
where $Φ(n)$ is the totient summatory function.

$∣F_{n}∣=1+Φ(n)$

A good definition is by using Dedekind cuts.