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## 'More Marbles' printed from http://nrich.maths.org/

This problem follows on from

Marbles
Suppose I start with four marbles, one of each colour red, blue,
green and yellow.

When I trade marbles I give away one marble of any colour and I
receive one marble of each of the other three colours.

Can I trade marbles so that I will have exactly two marbles of each
colour?

Can I have equal even numbers of each colour after a number of
trades?

What about ending up with 5 marbles of each colour?

Is this possible and if so how many trades does it take?

Is it possible to end up with the same odd number of each colour
for any odd number?