Permutation and CombinationHard
Question
Number of natural number upto one lakh, which contains 1,2,3, exactly once and remaining digits any time is -
Options
A.2940
B.2850
C.2775
D.2680
Solution
First fill 3 places by 1,2,3 in ways and then remaining one in 7 × 7 ways so total no. of ways
= 5P3 × 7 × 7 = 2940
= 5P3 × 7 × 7 = 2940
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