Elitmus
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how many no can be formed using digits (1,2,3,4,5,6,7,8,9)..such that 1234 is fixed and other no placed so that it's divisible by 11.
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- no. is divisible by 11 when difference b/w sum of odd places digit and sum of even places digit is equal to 0 or 11.
If we place 1234 at odd place we didn't get any digit which is divisible by 11
but when we place at even place we get the digit which is div. by 11
i.e 657123489{(6 + 7 + 2 + 4 + 9) - (5 + 1 + 3 + 8) = 11}, 912345687 or much more which we can find by combinations & permutation..
firstly 1234 we can arrange in 24 ways but we don't take 1 or 3 together and 2 or 4 anywhere in the digits together so there is only 12 ways.
now rest 7, 5 are in even place and 6 , 8 , 9 are in odd place anywhere in the digits we get 20 ways.
total ways 20 + 12 = 32.
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