Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationFundamental PrincipleMedium2 minQB

MathematicsMediumsingle choice

The number of 5 digit numbers that contain 7 exactly once is

Answer:

Solution:

5 digit numbers having 7 in $1^{st}$ place $= 9^{4}$

In $2^{nd}, 3^{rd}, 4^{th}, 5^{th}$ places is $4 \times 8 \times 9^{3}$

Total number of 5 digit numbers having 7 exactly once is $= 41 (9^{3})$

Stream:JEESubject:MathematicsTopic:Permutation & CombinationSubtopic:Fundamental Principle

⏱ 2mℹ️ Source: QB

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