how many four digit even numbers can be formed from the digits (2,4,6,7,9) if no digit is used more than once?

Question

anonymous · Answer

Lets see. To be even it has to end in an even number.
So we have 4 positions where we can place numbers. Lets start from the back.

_ _ _ _
1 2 3 4  st/th/nd/rd dight

4th digit: 3 options
3rd digit: 4 options
2nd digit: 3 options
1st digit: 2 options

3*4*3*2 = 72 numbers

anonymous · Answer

why are there 4 options for the 3rd digit?

anonymous · Answer

Because you used one of the even digit. Since you had 5 digits to begin with now you are down one and so have 4 options since the 3rd digit can be either odd or even. The 4th digit it the only special case

anonymous · Answer

omg i get it! thank you so much!! :')

anonymous · Answer

are  you always on this? 0.0

anonymous · Answer

No, actually just found it again after several months. I was supposed to be doing my coursework too >_<

anonymous · Answer

well crap x.x lmfaooo why are u helping other people then?? .-. (not complaining!)

anonymous · Answer

Procrastinating essentially.

anonymous · Answer

story of my life yo xD