What are the finger numbers used in piano lessons?

According to instruction captured in a piano lesson transcript, fingers are numbered as follows for both hands:

• 1 — Thumb (noted as a helpful rhyme: "thumb and one, they kind of rhyme")
• 2 — Index finger
• 3 — Middle finger
• 4 — Ring finger
• 5 — Pinky finger

These numbers are used to indicate which fingers to use when playing specific keys or exercises.