Questions about $GL_n(\textbf F)/SL_n(\textbf F)$.

Question

I learned that the special linear group is a normal subgroup of the general linear group. That is, $SL_n(\textbf F) \lhd GL_n(\textbf F)$. It is quite obvious since $\det(ABA^{-1})=\det(B)=1$ where $A \in GL_n(\textbf F)$ and $B\in SL_n(\textbf F)$. I wonder about what does the quotient group $GL_n(\textbf F)/SL_n(\textbf F)$ equal to? or just about the order of this quotient group. I need your help.