Question

How many different numbers can be formed with the digits $1,3,5,7,9$

• A. $325$
• B. $576$
• C. $625$
• D. $525$

Answer 1

Answer: (A)

$325$

Single digit number 1,3,5,7,9 $=5$

2 digit number ${=}^5{C}_2\times 2!=20$

3 digit number ${}^5{C}_3\times 3!=60$

4 digit number ${}^5{C}_4\times 4!=120$

5 digit number $5!=120$

Total numbers $20+60+120+120+5=325$