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 (Junior) / 2021 / SA2 / Paper 2 – Q08 [3 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2022/05/P6_SA2_2021_ACS_Junior_Paper2_Q08-Qns.jpg?resize=400%2C260&ssl=1)
![P6 / Maris Stella / 2020 / SA2 Prelims / Paper 1 – Q07 [1 mark]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2021/12/P6_SA2_2020_Maris_Stella_Paper1_Q07-Qns.jpg?resize=400%2C260&ssl=1)