Question:
Mr Kim had forgotten his 3-digit passcode for logging into his laptop. However, he remembered that the passcode contained three out of these four digits, 2, 4, 7 and 8. None of the digits were repeated. He tried 247 and 274 but both passcodes were incorrect. At most, how many more passcodes could he make?
Solution:
![P6 / ACS / 2019 / CA1 – Q06 [2 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2021/01/P6_ACS_2019_CA1_Q06-Qns.jpg?resize=400%2C260&ssl=1)
![P6 / Nan Hua / 2021 / SA2 /
Paper 2 – Q13 [5 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2022/08/P6_SA2_2021_Nan_Hua_Paper2_Q13-Qns.jpg?resize=400%2C260&ssl=1)