I have two questions:
1) How can I divide an entire list of numbers by three and only keep the remainder? I also want to keep track what number correlates to that new data set.
2)What other resources would I use for this kind of question? I do not want to ask people and have to wait for answer every time a question arrises.
example
data = RandomInteger[{1, 100}, {20}]; {data, Map[Mod[#, 3] &, data]}
or even
{data,Mod[data,3]}
See the command http://reference.wolfram.com/language/ref/QuotientRemainder.html for examples
