If the quarks in a neutron are (up,down,down), why isn't it negatively charged? Excuse the silly question, just wondering.
The up quark has a charge of $+2/3$, the down has a charge of $-1/3$. If you have a bound state of charged particles, the total charge is just the charge of the elementary constituents. The neutron consists of one up quark and two down quarks, so the total charge $Q$ is:
$$Q = 2/3 + 2 \times (-1/3) = 0$$
The names up and down don't refer to electric charge $Q$ but are rather references to isospin charge $I_3$.