The total number of natural numbers of 6 digits that can be made with digits 1,2,3,4 if all digits are to appear in at least once are........
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3 Answers
62case 1 : 1 digit thrice 3 digits once:
no of ways =4C1×3C3×6!/3!
case 2: 2 digits twice 2 digits once:
no of ways =4C2×2C2×6!/(2!.2!)
case 3: 3 digits twice:
no of ways =4C3×6!/(2!.2!.2!)
Take the sum...
621) 480
2) 1080
3) 360
So the basic is that The 3rd case cant be taken!!
That is because the 3 digits are not used...
So sum of 1st two parts give the answer :)