Question

Number of seven digit numbers, which can be formed with non-zero distinct digits such that it starts and end with a prime digit and middle digit is an even digit, is-

• A. 17280
• B. 15120
• C. 12960
• D. 21600

Answer 1

Answer: (B)

Csae-I: If middle digit is $2$
then numbers $\mathrm{3.2.6.5.4.3}=2160$
Case-II: If middle digit is not $2$
then number of $\mathrm{4.3.3.6.5.4.3.}=12960$
So total number of 7 -digit numbers
$2160+12960=15120$