Question

5 digit no is to be formed using 0-9 Repetition is not allowed​

Answer 1

Answer:

The trick is to realize that a number can not start with a zero! Now, there are 105 ways in which the digits 0-9 can be chosen for the five places of a five digit number. Out of these, 104 start with zero (once we start with 0, there are only 4 slots to fill, where we have 10 choices each).

Answer 2

Answer:

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