G, D and F major

G major

Start the pattern on G and one step goes wrong. F to G is a tone, but 7 to 8 must be a semitone. So G major needs F sharp, so that 7 to 8 (F sharp to G) is a semitone.

D major

Start on D, and two notes need a sharp. D major needs F sharp and C sharp. Each sharp puts a semitone back where the pattern wants it.

F major

Start on F, and A to B is a tone. But 3 to 4 must be a semitone. So F major needs B flat, so that 3 to 4 (A to B flat) is a semitone.

Remember

• G major: F sharp.
• D major: F sharp and C sharp.
• F major: B flat.