= Solution
Using the measured single-flavor leptonic <partial decay width> as one unit,
$$
\boxed{N_{\rm eff}=\frac{\Gamma_W}{\Gamma(W\to e\nu)}
=\frac{2085}{232}=8.987\simeq9.}
$$
This agrees with three leptonic channels plus six color-distinguishable <quark> channels in the leading massless approximation. The six <quark> units are two accessible up-type flavors times three <color charges>, with the sums of squared <CKM matrix> elements over down-type partners approximately unity. They are not nine generations or nine new flavors. Small mass and <Quantum chromodynamics> radiative corrections prevent the ratio from being an exactly integer channel count.
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