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An n-digit numberis a positive number with exactly`n`digits. Ninehundred distinct n-digit numbers are to be formed using only the three digits2, 5, and 7. The smallest value of `n`for whichthis is possible isa.`6`b. `7`c. `8`d. `9`A. 6B. 7C. 8D. 9 |
Answer» Correct Answer - B Distinct n - digit numbers which can be formed using digits 2, 5 and 7 are `3^(n)`. We have to find n, so that `3^(n) ge 900` `rArr" " 3^(n - 2) ge 100` `rArr" " n - 2 ge 5` `rArr" " n ge 7`, so the least value of n is 7. |
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