Number of four digit numbers that can be formed using all the digits except zero such that every number has exactly 2 distinct digits in it is

Question

Accepted Answer

Correct answer: D. (d) Two distinct digits can be choosen out of 9 digits is in ^9C_2=36 ways now we can form 2^4 different 4 digit numbers from which wecan excludethe two cases ⇒36 (2^4-2)=36 (16-2 )=504

$Number of four digit numbers that can be formed using all the digits except zero such that every number has exactly 2 distinct digits in it is$

Solution

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