Hayley was gifted a new mobile phone for Christmas and has been busy setting it up.
Hayley is choosing a 4-digit security code.
Each digit is a whole number from 0 to 9
She decides all her digits will be odd numbers and no digits will be repeated.
How many different codes can she make?
Answer:
For the first digit the number of possibilities is 5 (9,7,5,3,1)
For the second digit the number of possibilities is 4 since one odd number will be the first digit
The third will be 3 and the fourth 2
Therefore, the total number of possibilities is 5 x 4 x 3 x 2 or 120.