How can i calculate the height of number in this triangular? Given this triangular:
$$1$$
$$2,3$$
$$4,5,6$$
$$7,8,9,10$$
$$.............$$  
Now, how can i calculate the height of number of some number in this triangular? (Namely, how can i find formula for the height of $n$?)

For a given value $n$ there exist $h$ such that 
\begin{eqnarray*}
\frac{h(h-1)}{2} < n \leq \frac{h(h+1)}{2}.
\end{eqnarray*}
Now treat the the right hand in equality as a quadratic in $h$ and solve to get
\begin{eqnarray*}
h = \left\lceil \frac{-1 + \sqrt{1+8n}}{2} \right\rceil.
\end{eqnarray*}
