Submit a question to our community and get an answer from real people.

You have a rabbit, a ferret, a gerbil, and a turtle. In how many diff orders can they be fed?

Kevin has a rabbit, a ferret, a gerbil, and a turtle. He feeds them in a different order each day. In how many different orders can Kevin feed his pets?
4th grade math for my daughter and I know there has got to be some kind of simple equation or easy way to do this instead of writing them all out which I have been doing for a lot of the other ones and I know there is an easier way to explain it to her.

Report as

there are 4 choices to do the order. all you have to do is multiply.

ex. there 4 animals to fill in 4 feeding spots:

there are 4 options for the first spot. because you cannot do the same one twice, the second spot has 3 options, the third one has 2 options, which means there is one left to fill in the last spot.
4x3x2x1
24
there are 24 different orders that the animals can be fed.

a simpler way to do it is by the following rule:
if the number of spots is the same as the number of options, it can be written as x!

with the example from before, it would be 4!

this will not work if the number of spots and the number of options are different. if they are different, it stops with the number of spots available.

ex: 6 people are running in a race. only first, second, and third places will receive prizes. how many different orders can the three prize winners come in?

there are three spots. there are 6 options for the first spot, 5 options for the second, and 4 for the third.
6x5x4
120
there are 120 different orders the three prize winners can come in.

Report as
Thank you very much! Great explanation, examples, and fast reply!
Thanks again!
Report as
No prob! Math is one of my best subjects... I was happy to help.
Report as
I have one more just like the last one if you don't mind... I just want to make sure I am doing this right. It's been too many years. lol....
3 different banks
a pig, a cow, a horse
how many ways can he arrange the banks on the shelf?
so it would: 3x2x1=6?
Report as

This sounds like a factorial, such that there are
4 possible starting values
3 possible second-choices (for each of the starters)
2 possible 3rd choices...
and only 1 possible last place (for each set of the above)
so: 4 * 3 * 2 * 1 = 24

Report as
Kevin may have fewer choices if he elects to keep his gerbil in the same cage as his ferret.
Report as
lol
Report as
So I REALLY appreciate your fast reply since school is starting in a few hours!!! LOL... What do you think the best way to explain it would be best for my 9 year old to understand? Sorry.. Hope that makes sense... NO sleep!
Report as
its my pleasure! read TheaterGeek's response- that is an easy way to explain it to your 9year old =)
Report as
Thanks again Kristen!!
Report as
It's only but a pleasure! I'm glad i could help! =)
Report as
I have one more just like the last one if you don't mind... I just want to make sure I am doing this right. It's been too many years. lol....
3 different banks
a pig, a cow, a horse
how many ways can he arrange the banks on the shelf?
so it would: 3x2x1=6?
Report as
thats the one =)
Report as