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In page Musical note:

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The remaining five notes of the chromatic scale (the black keys on a piano keyboard) were added gradually; the first being B, since B was flattened in certain modes to avoid the dissonant tritone interval. This change was not always shown in notation, but when written, B (B flat) was written as a Latin, cursive "𝒷", and B (B natural) a Gothic script (known as Blackletter) or "hard-edged" 𝔟. These evolved into the modern flat () and natural () symbols respectively. The sharp symbol arose from a ƀ (barred b), called the "cancelled b".[citation needed]