Old math teachers never die, they just become irrational.
Old math teachers never die, they just tend to infinity.
Old math teachers never die; they just become angles.
Old math teachers never die, they just reduce to lowest terms.
Old math teachers never die; they just pass into another sphere.
Old math teachers never die, they just disintegrate.
Old math teachers never die, they just go off on a tangent.
Old math teachers never die, they just use strange expressions.
Old math teachers never die, they just can't differentiate.
Old math teachers never die, they just lose their identities.
Old math teachers never die, they just lose some of their functions.
Old math teachers never die, they just subtract.