← Why Twelve Notes · Lesson 2 of 4
Tempo is a rate
Tempo is written in beats per minute. At 60 beats per minute each beat lasts one second; at 120 each beat lasts half a second. Doubling the tempo halves the time of every note.
That makes a song’s length a division problem: count the beats in the whole piece, then divide by the tempo.
A piece has 300 beats and is played at 100 beats per minute. How long does it last?
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