Fractions & exponents
12 semitones make an octave. Major scale steps: 2 2 1 2 2 2 1. Beats: whole 4, half 2, quarter 1, eighth ½. One beat lasts 60 ÷ BPM seconds.
Frequency: up an octave × 2, down ÷ 2. A4 = 440 Hz. Each semitone multiplies by 21/12 ≈ 1.0595, so n semitones above A4 is 440 × 2n/12.
One step
Count keys, beats and octaves.Count up
How many semitones from D up to A? From A up to the next D? What do they add up to?
Octaves
A4 is 440 Hz. What is A2? What is A6?
Fill a bar
How many eighth notes fill one bar of 4/4? Of 3/4? Of 6/8?
Beat length
At 100 BPM, how long is one beat? One bar of 4/4?
Two or three steps
Use the keyboard on p.8 to count.Song length
A song has 48 bars of 4/4 at 96 BPM. How long does it last, in seconds and minutes?
Build a scale
Use 2 2 1 2 2 2 1 from E to build E major. Which notes do you play, and how many black keys?
Chord menu
How many different sets of 4 notes can you choose from the 12 in an octave? Use 12 × 11 × 10 × 9 ÷ (4 × 3 × 2 × 1).
Pure or equal?
A pure fifth above A3 (220 Hz) is 3/2 × 220. Equal temperament gives E4 = 440 × 2−5/12. Find both. How far apart are they?
Circle of fifths
Start on G and go up a fifth (7 semitones) three times. Which notes do you visit? How many semitones is that in total?
Missing notes
Solve: a 3/4 bar has one quarter note plus x eighth notes. A 6/8 bar has one dotted quarter (3 eighths) plus x eighths.
Equations & exponents
A1–A2 (pp.17–18).Practice plan
Start a passage at 72 BPM and add 4 BPM a day: T = 72 + 4d. When do you reach 120 BPM?
Solve for tempo
A piece has 40 bars of 3/4 and lasts 80 s. Use t = 60 × beats ÷ BPM to find the tempo.
Low A
Solve 440 × 2k = 55. Which A is it?
Five up
D5 is 5 semitones above A4. Find its frequency. Then use n = 12 × log₂(f ÷ 440) to check that 880 Hz is 12 semitones up.
Your turn to be the composer
- Pick a piece you know, or invent 4 bars.
- Write a question about its rhythm, tempo, scale or pitch.
- Solve it, then play it, if you can, to check by ear.
My problem, and my worked answer:
Try every problem first, then check here. Wrong answers are useful: find the step where your work and the key split apart.
The key never prints with Print my work or Print blank. Open it to get its own Print the answer key button.
Answer key
Worked solutions. Frequencies use equal temperament with A4 = 440 Hz.