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 digit 2, 5 & 7. the smallest value of n for which this possible is? (2024)

The correct option is B

7

TFinding the smallest value of n:

Given,

Three digit number 2,5and7 with repetition, each place of n digit number can be chosen in 3 ways.

Hence, the total number of n-digit numbers=3×3×3...ntimes=3n

According to given condition

3n9003n-2100

Now, here we need to take the value of n which satisfies the left-hand side of the equation to the right-hand side.

Taking, n=6

34=8181100not satisfy the equation

Hence option (A) is incorrect

Therefore,

n-2=5n=7

Taking,

35=243243100which satisfies our equation.

Hence option (B) is correct.

Taking, n=8

36=729729100which satisfy our equation but 87

Hence, option (C) is incorrect.

Taking, n=9

37=21872187100which also satisfy the equation, but 97

Hence option (B) is correct.


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 digit 2, 5 & 7. the smallest value of n for which this possible is? (2024)

FAQs

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 digit 2, 5 & 7. the smallest value of n for which this possible is? ›

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. 6.

How many 3 digit numbers with distinct digits are there using digits 0 9? ›

We have 9 choices for the first digit (which cannot be 0). Then we have 9 choices (including 0) for the second digit. Then 8 choices for the third digit. Therefore, we can form 9*9*8 = 648 3-digit numbers of distinct digits.

How many 9 digit numbers are there in which all the digits are distinct? ›

Hence, 9 digit numbers of different digits can be formed in 3265920 ways.

How many numbers can be formed with the digits 1, 2, 3, 4, 3, 2, 1 taken all together? ›

Hence, the required number of numbers = (6×3)=18. Q.

How many 5 digit numbers can be formed from 12345 divisible by 3? ›

A five digit number divisible by 3 is to be formed using the digits 0,1,2,3,4 and 5, without repetition. The total number of ways this can be done, is. 216.

How many combinations with 3 items no repeats? ›

While doing this, we keep in mind that order doesn't matter, so we don't use repeats such as {1,2,3} and {3,2,1}. These are all of the possible combinations of three numbers, and we see that there are seven combinations in this list. Therefore, there are 7 combinations possible with 3 numbers.

How many distinct 3-digit numbers are there? ›

You can also think it this way: You have 9 ways to choose the first digit (it cannot be zero), 9 ways to choose the second (it can be zero but it cannot be the same as the first one) and 8 ways to choose the third one (it can be zero but it cannot be the same as the first or second one). Total: 9×9×8=648.

How many digits is 9 digit number? ›

9 digit numbers are those numbers that have 9 digits in them and they start from the number 100000000 and end on 999999999. There are a total of 900 million, 9-digit numbers.

How many combinations are 9 digits? ›

How many combinations are there in a 9-digit password? - Quora. I'm going to assume you mean traditional digits (from 0 to 9). In this case, there are 10 to the power of 9 possible passwords, since there are 9 spots, and we can select 10 possibilities in each of them. This is equal to 1,000,000,000 (1 billion).

What is an example of a 9 digit number? ›

The number 916238457 is an example of nine digit number which contains each of the digit 1 to 9 exactly once.

How many numbers can be formed with the digits 2, 3, 4, 5, 4, 3, 2 so that the odd digits occupy the odd places? ›

Required number of numbers = ( 3 × 6 ) = 18 . Was this answer helpful?

How many 3-digit numbers can be formed with the digits 1 2 3 4 and 5 which are divisible by 5 and in which the digits are not repeated? ›

Thus, 3-digit numbers can be formed in 60 ways without repetition. Q.

How many numbers can be formed using the digits 1 2 3 4 and 5 such that no digit is repeated? ›

Total Number of Numbers which can be formed by numbers 1,2,3,4,5 (without repeating digitsi) = 5*4*3*2*! = 5! = 120.

How many 3 digit numbers divisible by 5 from 100 to 999? ›

Hence, 180 three digit natural numbers are divisible by 5. Q.

How many 5 digit numbers can be formed using the digits 1, 2, 3, 4, and 5 without repetition? ›

Number of such numbers =120.

How many two-digit numbers can you make with 1, 2, 3, 4 without repeating the digits? ›

By using the concept of fundamental principle of multiplication we get the total such numbers as 4 × 3 = 12. So a total of 12 two digit number can be generated by any of the 4 digits. Hope it helps!

How many 3 digit numbers can be formed using 0 9? ›

The units place can be filled with 0 to 9 ways. i.e., 10 ways. So a total of 9 * 10* 10 = 900 three digit numbers can be formed.

How many 3 digit numbers from 0 to 9? ›

If what you want are all possible three digit numbers with no repetition of the digits then you have 10 choices for the first digit, you have 9 choices for the 2nd digit, and you have 8 choices for the 3rd digit giving you 10x9x8 = 720 in all.

What is the combination of 3 digits from 0 to 9? ›

If you are meaning simply a 3 digit number using digits 0–9 then the answer is 10•10•10 = 1,000 with repetition. 10•9•8 = 720 without repetitions.

How many 3 digit numbers can be formed using the digits 1 to 9? ›

for each digit you have 9 possibilities to use a number between 1 and 9, so the total number of 3-digits numbers is 9 * 9 * 9 = 729. when you take all numbers between 1 and 999 (which is the largest 3-digit number), you get 999 in total, obviously.

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