Question

Number of $5$ digit numbers that can be made using the digits $1$ and $2$ and in which at least one digit is different.

• A. 30
• B. 25
• C. 28
• D. 31

Answer 1

Answer: (A)

Total number of numbers without restriction $=2^5$
Two numbers have all the digits equal. So,
The required number $=2^5-2=30$