I need to draw the derived tree for $1-2-(3-4)*5*6$ from the grammar below. I want to know how many possibility derived tree are there from this grammar.
$$\begin{align}V_n&=\{expr,term,factor,number\}\\ V_t&= \{(,),-,*,0...9\}\\ P&=\left \{ \begin{aligned} expr&\to expr-expr\;\mid\;term\\ term&\to term*factor\;\mid\;factor\\ factor&\to number \;\mid\; (expr) \\ number&\to 0|1|2|3|4|5|6|7|8|9 \end{aligned} \right \}\\ S&=expr \end{align} $$
The possbilities that I can find are:
$$(1-2)-(((3-4)*5)*6)\\ 1-(2-( ((3-4)*5) *6))$$
Are there other possibilities?
The ambiguity in your grammar is limited to the production $expr\to expr - expr$; the production for multiplication is unambiguously left-associative. So in this particular case, there are only two possible parses, as you have indicated.