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.
It has 12 faces, which meet in 30 edges; these intersect in threes to form 20 vertices.
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."
The wounded crept together in twos and threes and one could hear their distressing screams and groans, sometimes feigned--or so it seemed to Rostov.
The officers, as usual, lived in twos and threes in the roofless, half- ruined houses.
Behind them along the narrow, sodden, cutup forest road came hussars in threes and fours, and then Cossacks: some in felt cloaks, some in French greatcoats, and some with horsecloths over their heads.
Pierre walked along, looking from side to side, counting his steps in threes, and reckoning them off on his fingers.