Right hand: thumb corresponds to 1 (notation), index finger corresponds to 2 (notation), middle finger corresponds to 3 (notation), ring finger corresponds to 4 (notation) and little finger corresponds to 5 (notation).

left hand: thumb corresponds to 5 (notation), index finger corresponds to 4 (notation), middle finger corresponds to 3 (notation), ring finger corresponds to 2 (notation), and little finger corresponds to 1 (notation).

Remarks: It depends on what the key signature of the notation is, that is to say, first of all, it is necessary to make clear what key it is, and it is also possible to refer to the first tone of the music or the tonic.

Extended information:

Piano (Italian: pianoforte) is a keyboard instrument in western classical music, and has the reputation of "the king of musical instruments". It consists of 88 keys (52 white keys and 36 black keys) and a metal chord soundboard. Italian Bartolomeo Cristofori (1655-1731) invented the piano in 179.

The piano has a range from A(27.5Hz) to C8(4186Hz), which covers almost all the musical sounds in the musical system. It is the instrument with the widest range except the organ. Piano is widely used in solo, ensemble, accompaniment and other performances, and it is very convenient to compose and rehearse music. By pressing the keys on the keyboard, the player affects the mallet wrapped in felt inside the piano, and then hits the steel wire string to make a sound. The piano needs regular care to keep its tone unchanged.

References:

Piano-Baidu Encyclopedia