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A number lock on a suitcase has three wh...

A number lock on a suitcase has three wheels each labelled with ten digits 0 to 9. If opening of the lock is a particular sequence of three digits with no repeats, how many such sequences will be possible? Also, find the number of unsuccessful attempts to open the lock.

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On the first wheel, there can be 10 digits.
On the second wheel, there will be one of the 9 digits and on the third wheel, there will be 8 digits.
Therefore, the number of numbers is `10xx9xx8=720`
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