Question

How many 5 digit no. can b formed wit digits 1, 2, 3,4,5,6 which r divisible by 4 and digits not repeated?

Answer 1

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here is your answer
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➡The answer is 192. 

➡Well here is the solution:-Take 5 blanks _ _ _ _ _. 

➡Since the number has to be divisible by 4 we can have only the following cases 

➡12,16,24,32,36,52,56,64.That is you can fill the last two blanks in eight ways. 

➡Now take the first three blanks.Since we already selected 2 numbers,we are left with 4 numbers. 

➡That is we can fill the first blank in 4 ways,similarly the second in 3,the third in 2 ways. 

➡By fundamental principle of counting we have to multiply all of them. 
That is 4 x 3 x 2 x 8=192.
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Answer 2

192
_ _ _ _ _ _
for divisible by 4 the last two digit must be divisible by 4.
12,16,24,32,36,52,56,64
there are 8 possibilities.
consider the first one--
 _ _ _ _ 1 2    we've fixed last two digit.so now we have 4*3*2 options for this one.
just like this there are 8 options to fix.
therefore there are 24*8=194