Your favorite CD consists of 12 songs. If you play the CD randoming on your CD player, how many play list are possible?
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The registration code for a new softwear game you purchased consists of a string of 3 letters followed by 5 digits. How many different registration codes are possible? If you lost your registration code and had to quess, what is the probability that you will answer the correct...
How many n-digit decimal sequences (using digits 0-9) are there with k 1s? Decimal sequences meaning you can have as many 0s in front of a number. For example: 000001234557891111 would be consider valid. So how do i come up with an equation? See my response to Sana's quest...