C on Piano: the Numbers It Answers To

Everything rooted on C, 62 qualities in 10 families. A chart will ask for three or four of them by number and leave the rest to the record, but the root is the part the number pins down, so this is the page a reader lands on first.

C answers to the 1, 2, 3, 4, 5, 6 and the 7 depending on what got called: it is a plain number in 7 of the twelve keys and needs an accidental in the other 5.

A piano player reads the whole chart at once — the instrument the numbers are usually written at, and the one that can voice a slash bass and the chord above it without asking anybody else to cover half of it. The digit is split between two hands on the same beat: whatever a slash mark puts under it goes to the left, the chord itself to the right, and a bare number leaves the left hand on the root.