Thread: Units in Z20

Make a list of units in Z20 and verify that they all map to units in Z4. Show that ther is a non-unit in Z20 that maps to a unit in Z4.

Please help... No idea how to do this...

Thanks in advance for any help

Originally Posted by jzellt

Make a list of units in Z20 and verify that they all map to units in Z4. Show that ther is a non-unit in Z20 that maps to a unit in Z4.

Please help... No idea how to do this...

Thanks in advance for any help

is a unit .

Therefore the group of units of is .

.

Now what kind of map are we talking about here? An isomorphism?

I'm not really sure what is meant by "map" either, but thanks for the reply. This will at least get me started...