the middle no. is atleast 4,(as all digits are distinct).
the remaining places filled by{0,1,2,3} in 4!-3!=18 ways.(1st place cant be 0)
1.if mid. no.=5,then the remaining 4 places have to be filled up by numbers from the set {0,1,2,3,4}.
therefore the no. of such numbers=5p4-4p3
2. middle position 6.rest places filled up from the set {0,1,2,3,4,5}
possibilities:6p4-5p3
3.middle no. 7
set of admissible no.s={0,1,2,3,4,5,6}
possibilities=7p4-6p3
4.middle no. 8
set of admissible no.s={1,2,3,4,5,6,7}
possibilities:8p4-7p3
5.middle position 9.
set of admissible no.s={0,1,2,3,4,5,6,7,8}
possibilities:9p4-8p3
Moderation Team
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