8. Let $A$ be any set of 7 real numbers, and let the set $B=\{x y \mid x, y \in A$ and $x \neq y\}$, denote the number of elements in set $B$ as $|B|$, then $|B|_{\text {max }}+|B|_{\text {min }}=$ $\qquad$ .
Obviously, $C_{7}^{2}=21$ is the maximum value of $|B|$, taking $A=\left\{1,2,2^{2}, 2^{4}, 2^{8}, 2^{16}, 2^{32}\right\}$, which satisfies the condition; if $|B|$ is the smallest, then $0 \in A, 1 \in A, -1 \in A$; at this point, for $0,1 \neq a \in A$, there must be $-a \in A, a^{2} \in A, -a^{2} \in A$, thus the set $A=\left\{0,1,-1, a,-a, a^{2},-a^{2}\right\}$.
Therefore, $B=\left\{0,-1, a,-a, a^{2},-a^{2}, a^{3},-a^{3},-a^{4}\right\} \Rightarrow|B|_{\min }=9$.
So, $|B|_{\max }+|B|_{\min }=21+9=30$.