HTML Entity - Sigma

Mistake: Confusing Greek lowercase letters with their Latin look-alikes

Fix: Greek ν (nu) looks like Latin v, Greek ρ (rho) looks like Latin p, Greek ω (omega) looks like Latin w. These are different characters with different Unicode values and distinct meanings in formulas.

Mistake: Using the wrong Greek letter for a standard scientific constant

Fix: Each scientific field has conventions: π for pi constant, μ for coefficient of friction, λ for wavelength, ρ for density, σ for standard deviation. Check the standard notation for your field.