Question

What is bigger 5/6 or 13/18?

Answer 1

To compare fractions, you need a common denominator.
6 goes into 18 three times.  If we multiply (5/6) by 3 on top and bottom you get
$\frac{15}{18}$
Now we can compare numerators, since 15 > 13
$\frac{5}{6} \ \textgreater \ \frac{13}{18}$