It can be easily calculated that the digits 0 to 9 can be arranged into 3628800 distinct ten-digit numbers.
But I also know how many of these numbers are prime.
*How many of these numbers* indicate to 0 to 9. The summation of 0 to 9 is 45. They are divisable by 3 and 9.
A 9-digit number has a property that the first 'n' digits are divisible by 'n'. There is no '0' in the number and all the digits in the number are distinct. What is the number?
How many 3-digit numbers can be formed from the digits 2, 3, 5, 6, 7 and 0, which are divisible by 5 and none of the digits is repeated?
Suppose 4 digits 2 ,4,6 and 9 are given.
You have to make a four-digit number.
In how many ways it can be done, if repetition of the numbers does not allowed?