playing with a full deck of cards

English as a Second Language English Teacher Explanations (ESL Tests)
1

English Language Tests, Intermediate level

ESL/EFL Test #291 [color=blue]“English Slang Idioms (13)”, question 7

He knew he couldn’t make that decision until he had more information. He knew he wasn’t … with a full deck of cards.

(a) shuffling
(b) gambling
(c) playing
(d) building

English Language Tests, Intermediate level

ESL/EFL Test #291 [color=blue]“English Slang Idioms (13)”, answer 7

He knew he couldn’t make that decision until he had more information. He knew he wasn’t playing with a full deck of cards.

Correct answer: (c) playing
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I’ve mistaken because I thought of real card playing.And I can’t really shuffle with a full deck /pack/ of cards I divide it into halves.

Now I found the solution:" not playing a full deck" is a derogatory phrase which allude to someone who is “having a bit missing” or “not all there” so to say it’s a stupid figure. /from: The phrases finder/ I don’t agree with this statement; instead I think:absent-minded. What is your opinion ?

2

I agree. The idiom has another, more common meaning: simple-minded.

3

what does it mean:He knew he wasn’t playing with a full deck of cards

I have found only:not be playing with a full deck.

thanks

4

He is not playing with a full deck = he is simple minded.

Here, it appears that the test setter has decided that
not playing with a full deck of cards = not having all the information
As Mister Micawber points out, that is not the usual meaning and so it is a little misleading that it is used in that way.