Ternary

Perhaps the prettiest number system of all is the balanced ternary notation

Sodic hydroxide, NaOH, is a ternary compound.

An "if…then…else" construction is called a ternary operator when it is combined in one line of a program.

And albeit these thynges be waighty and truthes of great importance, yet (by the infinite goodnes of the Almighty Ternarie,) Artificiall Methods and easy wayes are made, by which the zelous Philosopher, may wyn nere this Riuerish Ida, this Mountayne of Contemplation […] .