Find the number of 4 digit numbers that can be formed using the digits 1,2,3,4,5 if no digit is repeated. How many of these will be even?

Explanation

(i)There are 5 ways to fill the numbers

Since, repetition is not allowed, tens place can be filled by remaining 4 digits.

So, there are 4 ways to fill ten's place.

Similarly hundreds place can be filled by remaining 3 digits .

Similarly, to fill thousand's place, we have 2 digits remaining.

So, required number of ways in which four digit numbers can be formed from
the given digits is `5xx4xx3xx2=120`


(ii) Now, for the number to be even , ones place can be filled by 2 or 4.

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