1,2,3,4 1+2+3+4=10 4 times 3 times 2 times 1 =24 24 counting numbers
4,536 whole numbers or mixed numbers. 5,040 pure decimals.
1235; 1253; 1325; 1352; 1523; 1532; 2135; 2153; 2315; 2351; 2513; 2531; 3125; 3152; 3215; 3251; 3512; 3521; 5123; 5132; 5213; 5231; 5312; 5321. These are 24 such numbers which have four distinct nonzero digits and add up to 11.
For a 3 digit number, the left most or the most significant digit cannot be zero. So it can be 1,2,3,4,5,6,7,8 or 9 which is 9 possibilities. The middle number can be 0,1,2,3,4,5,6,7,8,9 which is 10 possibilties but one of the digits has been chosen already as the first digit, so the possibilities are only 9. The right most number can be 0,1,2,3,4,5,6,7,8,9 which is 10 possibilities but two of the digits have been already used by the left most and the middle digits. That leaves only 8 possibilities. So the total number of three digit numbers that have three distinct digits is 9 x 9 x 8 = 81 x 8 = 648 possibilities
There are 5*4*3 = 60 such numbers.
There are only five distinct odd digits.
5555
Since the numbers begin with 123, they all contain a 3. As a result, they all "contain 3 or 7". So the remaining 4 digits can be any digits and this gives 104 = 10,000 such numbers.
1,2,3,4 1+2+3+4=10 4 times 3 times 2 times 1 =24 24 counting numbers
4,536 whole numbers or mixed numbers. 5,040 pure decimals.
There are nine numbers which contain only one digit. There are 90 numbers which contain two digits. There are 900 numbers which contain three digits. There is one number which contains four digits.Therefore, the number of digits is equal to (9x1)+(90x2)+(900x3)+4 = 2893 digits. If this includes spaces, there would be 999 spaces, therefore there would be 3892 keystrokes.
California inmate ID numbers contain six digits.
874
100122 or, if negative numbers are permitted, -998877
Most credit cards in the United States contain 16 digits broken into four groups of four digits. American Express cards contain 15 digits, however.
45 percent are both even and odd digits
120 There are 6 digits in total. The numbers with 3 digits, with all digits distinct from each other, are the permutations of the 6 digits taken 3 at a time, and therefore there are 6*5*4 = 120 of them.