840 As with any puzzle of this type, you need to work out how many ways there are of choosing the first digit. The you multiply that by the number of ways of choosing the second digit, then you multiply that by the number of ways of choosing the third digit, etc So, there are seven different digits available to be chosen for the first digit. Then there are six left to be chosen for the second.... and so on. This gives us 7 x 6 x 5 x 4 which equals 840.
To form a five-digit number using the digits 1, 2, 3, 4, and 5, each digit must be used exactly once. Since there are 5 unique digits, the total number of different five-digit numbers that can be formed is given by the factorial of the number of digits, which is 5! = 120. Therefore, 120 different five-digit numbers can be formed using the digits 12345.
99999
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
500
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.
To form a five-digit number using the digits 1, 2, 3, 4, and 5, each digit must be used exactly once. Since there are 5 unique digits, the total number of different five-digit numbers that can be formed is given by the factorial of the number of digits, which is 5! = 120. Therefore, 120 different five-digit numbers can be formed using the digits 12345.
5040 different 4 digit numbers can be formed with the digits 123456789. This is assuming that no digits are repeated with each combination.
99999
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
500
24
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.
840
There are 60480 numbers.
5^4
1 set
It is 120 if the digits cannot be repeated.