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  • The number of 7-digit numbers which are multiples of 11 and are formed using all the digits 1,2,3,4,5,7 and 9 is________Option: 1 576<

The number of 7-digit numbers which are multiples of 11 and are formed using all the digits 1,2,3,4,5,7 and 9 is________

Option: 1

576


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

\mathrm{digits \equiv 1,2,3,4,5,7,9}\\

let number=\mathrm{a \;\;b\;\; c\;\; d\;\; e\;\; f\;\; g}

\mathrm{ (a+c+e+g) \sim(b+d+f)=11 k}

Case-1\mathrm{ \begin{aligned} &a+c+e+g=21 &&&&&&&,b+d+f=10\\ &(9,7,1,4),(9,7,2,3) \\ &(9,5,3,4) \end{aligned} }

Total number in this case =\mathrm{(4 ! \times 3 !) \times 3=432}

case-2

\mathrm{ \begin{aligned} &a+c+e+g=10&&&&&,b+d+f=21 \\ &(1,2,3,4) \\ \end{aligned} }

Total number in this case =\mathrm{ 432+144=576 }

Posted by

avinash.dongre

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