Question

How many 4-digit numbers can be formed using the digits 1,2,3,4,5,6,7,8,9 and 0?No digit can be used more than once.Show your work

Answer 1

To solve this problem, we have to multiply the possible number in each digit.

So, the thousand's place has 9 options because zero can take this place. The hundred's place has 9 options too because we already used a digit on thousand's place. Then, there are 8 options for ten's place, and at last, there are 7 options for unit's place.

Now, we just have to multiply

`9*9*8*7=4,536`

Hence, the are 4,536 possible 4-digit numbers.