If a sample of a radioactive isotope has a half life of 1 day how much remains at the end of the second day and at the end of the third day?

If a sample of a radioactive isotope has a half life of 1 day, then there will be one half of the original sample left after one day, and one quarter (one half of one half) left after two days, and one eighth (one half of one half of one half) after three days.