JEE Main 2023 (Online) 24th January Morning ShiftQuestion 1
The number of $9$ digit numbers, that can be formed using all the digits of the number $123412341$ so that the even digits occupy only even places, is ______
Permutation and Combination
Answer$60$
Solution
The even digits $2,2,4,4$ fill the $4$ even places in $\frac{4!}{2!2!}=6$ ways; $1,1,1,3,3$ fill the odd places in $\frac{5!}{3!2!}=10$ ways. Total $60$.