How many four digit PIN numbers can be made using only the digits 2, 3 and 4 and using each of these digits at least once in each PIN number?

Question

How many four digit PIN numbers can be made using only the digits 2, 3 and 4 and using each of these digits at least once in each PIN number? (A) 24 (B) 36 (C) 48 (D) 72

Tardigrade Admin · Accepted Answer

2234 or 2334 or 2344 ⇒ 3 ⋅ (4 !/2 !)=36

Q. How many four digit PIN numbers can be made using only the digits 2, 3 and 4 and using each of these digits at least once in each PIN number?

24

36

48

72

2234 or 2334 or $2344 \Rightarrow 3 \cdot \frac{4 !}{2 !} = 36$

Q. How many four digit PIN numbers can be made using only the digits 2, 3 and 4 and using each of these digits at least once in each PIN number?

24

36

48

72

2234 or 2334 or 2344⇒3⋅2!4!​=36

2234 or 2334 or $2344 \Rightarrow 3 \cdot \frac{4 !}{2 !} = 36$