Yes, Monty can use the number line to find an equivalent fraction with a denominator greater than 6.
For Example,
Consider

The equivalent fraction of
is
.
So, yes you can represent
on a number line by putting 6 lines between 0 and 1 and Can Represent
by putting 34 lines between 0 and 1.
There is no effect of denominator to find equivalent fraction of any rational number, whether the denominator is greater than 6 or less than 6, but denominator should not be equal to Zero.
We can find equivalent fraction of any rational number , the denominator of that rational number should not be equal to Zero.