What is the chord formula for a C half diminished 7 chord and how is it constructed on the piano?

The chord formula for a C half diminished 7 chord is 1, b3, b5, b7. To construct this chord on the piano, start with a C note as the root, then lower the third (E) by a half step to Eb, lower the fifth (G) by a half step to Gb, and lower the seventh (B) by a half step to Bb. This creates the C half diminished 7 chord.