The parts of the flower are most frequently arranged in fives, or multiples of fives; for instance, a common arrangement is as follows, - five sepals, succeeded by five petals, ten stamens in two sets of five, and five or fewer carpels; an arrangement in fours is less frequent, while the arrangement in threes, so common in monocotyledons, is rare in dicotyledons.
The whole theory of the inflections of a cubic curve is discussed in a very interesting manner by means of the canonical form of the equation x +y +z +6lxyz= o; and in particular a proof is given of Plucker's theorem that the nine points of inflection of a cubic curve lie by threes in twelve lines.
Later I said, "Make fifteen threes and count."
I wished her to make the groups of threes and supposed she would then have to count them in order to know what number fifteen threes would make.
But instantly she spelled the answer: "Fifteen threes make forty-five."
How would you define threes? Add your definition here.