There are 3024 of them.
27 if the digits can be repeated. 6 if not.
16.2 16 digit numbers and 2 digit decimal places.
There are 720 of them. The three digit counting numbers are 100-999. All multiples of 5 have their last digit as 0 or 5. There are 9 possible numbers {1-9} for the first digit, There are 10 possible numbers {0-9} for each of the first digits, There are 8 possible numbers {1-4, 6-9} for each of the first two digits, Making 9 x 10 x 8 = 720 possible 3 digit counting numbers not multiples of 5.
875
When the units digit equals the tens digit then the sum of the digits of a 2 digit number is double the units digit. In each tens range above 50, numbers below this critical point meet the requirement, numbers above this critical point have a sum LESS than double the units digit. The applicable numbers are 51-54 (4), 61-65 (5), 71-76 (6), 81-87 (7) and 91-98 (8). Then there are 4 + 5 + 6 + 7 + 8 = 30 qualifying numbers.
5040 different 4 digit numbers can be formed with the digits 123456789. This is assuming that no digits are repeated with each combination.
There are 60480 numbers.
There are 504 such numbers.
-123456787
To form a two-digit odd number using the digits 123456789 without repetition, the unit's digit must be an odd number. The available odd digits are 1, 3, 5, 7, and 9, giving us 5 options for the unit's place. For the ten's place, we can choose any of the remaining 8 digits. Therefore, the total number of two-digit odd numbers is (5 \times 8 = 40).
-123456786
A number divisible by 123456789 must be 0 or bigger than 123456789. It must, therefore have 1 digit or 9 digits (or more). A remainder of 1 makes no difference to the number of digits. In any case, there can be no number of 4 digits that is divisible by 123456789.
The largest digit in the number 123456789 is 9. Since the question asks for the largest number, 123456789 itself is the largest when considering all the digits together. However, if referring to individual digits, the maximum single digit is 9.
27 three digit numbers from the digits 3, 5, 7 including repetitions.
24
500
840