Both are ok, but this is a little strange thing. If you use "read" the numbers have to be written so they can read them. The movie version of hospital anaesthetics was always "Now I want you to count backwards from 100 for me".

They both have different meanings. In fact count 123 doesn't make much sense. You say count apples or eggs. Count means to calculate the number. Now counting itself maybe done through doing 123 or even another way. Whereas read 123 means asking someone to say 123 till wherever you meant. And to me its totally polite to say read 123 for me. You can make it more polite by adding Please i.e. Please, read 123 for me.

Hi, For me the correct thing to say would be, 'Count up to 3 for me, please'. 'To read' is something you do silently in your head. 'To read aloud' is when you read and speak the words at the same time. Hope this helps.