Total possible 4-digit numbers= 1000, 1001,...,9999 = 9000
Total with same digit numbers = 1111,2222,...,9999 = 9
9000 - 9 = 8991
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
64 if repetition is allowed.24 if repetition is not allowed.
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
125
pizza
64 if repetition is allowed.24 if repetition is not allowed.
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
125
pizza
There are 2000 such numbers.
9 odd numbers less than 100 can be formed. They are: 3,5,7,35,37,53,57,73 and 75.
Assuming the question refers to the digits 1, 2, ... , 9 the answer is 1344 numbers.
Numbers formed should be of at least 3 digits means they may be of 3 digits, 4 digits, 5 digits or 6 digits. There are 6 choices for digit in the units place. There are 5 and 4 choices for digits in ten and hundred’s place respectively. So, total number of ways by which 3 digits numbers can be formed = 6.5.4 = 120 Similarly, the total no.of ways by which 4 digits numbers can be formed = 6.5.4.3 = 360. the total no. of ways by which 5 digits numbers can be formed = 6.5.4.3.2 = 720. The total no.of ways by which 4 digits numbers can be formed = 6.5.4.3.2.1 = 720. So, total no.of ways by which the numbers of at least 3 digits can be formed = 120 + 360 + 720 + 720 = 1920.
2,401
There are 25 such numbers.
Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77