3Ans - (b)
But I am getting (d).
need an explaination.....
Nine hundred distinct N-digits numbers are to be formed by using 6,8,and 9 only.The smallest value of N for which this is possible is
a) 6
b)7
c)8
d)9
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4 Answers
21let the number of digits in the number be n
see 1st digit can come 3 ways
second can come in 3 ways
similarly each digit can come in 3 ways
so total ways are 3.3.3.3.3.....n times=3n≥900
n≥7
so least value of n is 7
1No restrictions.
So 3n (as 3x3x3x3x3.....n times) ≥ 900
Now go for experimental method...u'll find that it is 7 for which N is least else 3^n becomes less than 900 for n=(6,5,4,...) .
So ans is 7 .
--------------- The Dark Knight
1ooooooooooo sorry i didn't see dat eragon has posted the answer already .