Question

How many four digits even numbers with distinct digits can be formed out of the digits 0,1,2,3,4,5,6 ?

Answer 1

This is one of the Basic question on Permutation and Combination.

Well this one deals with Permutation .

Lets check how to solve this:

consider: abcd to be a 4 digit number now lets fill in all possibilities to check how many numbers we can form.

d can be 0,2 or 6 (only then is abcd even!)

c can take any value(0,1,2,3,5,6 except the value we filled at d).No repetition

similarly:

b can take any value(0,1,2,3,5,6 except the value we filled at d and c)

a can take any value(0,1,2,3,5,6 except the value we filled at d,c and b)

Therefore we can have 3*5*4*3=180 numbers possible(3-d,5-c,4-b,3-a)!