86/1000, the small-angle approximation, sinθ≈θ

84/1000, infinity minus infinity, calculus 1 limit

80/1000, 1+1/2+1/3+1/4+...., the harmonic series diverges, calculus 2

Understand Calculus in 35 Minutes

85/1000, why is the integral of 1/x = ln(x)+C?

83/1000, don't use the quotient rule

82/1000, know the chain rule for derivatives!