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## Homework Statement

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

b)

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.