Example question: ml=+5 what is the lowest value of n? I can't seem to remember the easy trick to finding the relationship if someone could explain that would be great. -Thank you in advance.
Just work it out the proper way, in my opinion you shouldn't have to resort to shortcuts for such a question.
The magnetic quantum number $m_l$ takes values between $-l, -l+1, \cdots, l-1, l$. As such, as long as $l \geq 5$ then $m_l = 5$ will be valid.
The orbital angular momentum quantum number $l$ takes values between $0, 1, 2, \cdots, n-1$. Consequently if $n \geq 6$, then $l \geq 5$ and $m_l = 5$ is permissible. The smallest possible value of $n$ is therefore $6$.