A) how many numbers have distinct digits from 1000 to 9999?
B) how many odd numbers have distinct digits from 1000 to 9999?
The Attempt at a Solution
a) the first place value has choices from 1-9, the second has choices from 0-9 but one number was used in the first place value so it has 9 choices, third place has 8 choices and fourth place has 7 choices so
9*9*8*7 numbers = 4536 numbers with distinct digits
the available digits are 1,3,5,7,9
so first place has 5 choices, second has 4, third has 3, fourth has 2
so 5*4*3*2 numbers = 120 odd numbers with distinct digits.
that question seemed a little too easy so thats why I am posting it.