if a combination lock must contain 5 different digits, in how many ways can a code be formed from the digits 0 to 9.


Sagot :

At the first digit starting at the left, you have 10 possible ways.
Since the problem is not a repetition, the next digit has 9 possible ways.
Until the remaining next digits will 8, 7 and 6 ways.
Multiply them: 10*9*8*7*6=30240 ways