An n-digit number is a positive number with exactly n digits. Nine hundred distinct n-digit numbers are to be formed using only the three digits 2, 5, and 7. The smallest value of n for which this is possible is
The correct option is B 7 Distinct n-digit numbers which can be formed using digits 2,5,and8are3n. We have to find n so that 3n≥900or3n−2≥100orn−2≥5orn≥7 So the least value of n is 7.