Probability Question (1 Viewer)

[pacey0006]

Its probably really simple but i cant figure it out..

" How many different 4-digit numbers can be made from the digits 0 to 9 if a digit cannot be repeated. Note: A 4-digit number cannot begin with 0. "

Answers 4536, i have just have no idea how to work it out... (i suck at probability)

Thanksss

 

[Carrotsticks]

First one can have 9 options (1,2,3,4,5,6,7,8,9)

Second one can have 9 options (since one digit has gone to the first already, and we can now include 0)

Third one can have 8 options

Last one can have 7 options.

So total is 9x9x8x7 = 4536.

 

[Leffife]

Number of ways it can be formed is: 9P3 x 9 = 4536

OR

No. of ways = [9!/(9 - 3)!] x 9 = 4536.

Remember that this is a permutation, as order matters.

 

[pacey0006]

Thankss