We've seen that all undotted notes divide only in twos, fours, eights, etc. What if you want to fit three equal notes into the time of a single undotted quarter note?
You can do it by marking each group with the number "3," as follows:
The grouping is called a triplet, and the "3" indicates that an undotted note is to be divided into three equal parts. The above illustration shows how you would notate triplets having the time value of a half note, a quarter note, or an eighth note. In the Mozart example, three triplet eighth notes are played in the time of two normal eighth notes, i.e., in the time of a quarter note. The triplet accompaniment is especially effective here, used in contrast to the duple rhythm of the melody:
A rest, rather than a note, can be part of a triplet group and triplet rhythms can be varied with ties as in this example from Brahms' Third Symphony:
Figure 10. Quarter note triplets (Allegro, Brahms, Symphony no. 3)
Suggested Practica Musica activity: Reading Triplets. Practice reading music examples with triplet rhythms.