Let digits a, b, c be in A.P. Nine-digit numbers are to be formed using each of these three digits t

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8. Sequences and Series

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Let the digits $a, b, c$ be in $A.P.$ Nine-digit numbers are to be formed using each of these three digits thrice such that three consecutive digits are in $A.P.$ at least once. How many such numbers can be formed?

A

$1261$

B

$1262$

C

$1263$

D

$1260$

(JEE MAIN-2023)

Solution

$\frac{{ }^7 C _1 \times 2 \times 6 !}{2 ! 2 ! 2 !}=1260$

Standard 11

Mathematics

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