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A number lock has 4 wheels, each labelled with how many digits?
ATwo digits
BSix digits
CNine digits
DTen digits
Answer & Solution
Correct answer: D. Ten digits
1. The lock is the example that opens the topic.
2. Each wheel carries the full run of decimal digits.
3. The number lock has 4 wheels each labelled with 10 digits from 0 to 9.
4. So each wheel offers ten possibilities.
_Source: NCERT Class XI Mathematics, Ch 6 'Permutations and Combinations'_
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