Look at this cell phone. It's like a chameleon.

- What do you mean by that?
-It changes its color accoring to the temperature.
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Can we use "What's that supposed to mean?" instead of 'What do you mean by that?" Are both the same? When do we use "What's that supposed to mean?"

yes

Both sentences mean the same thing, yes. You can use either phrasing whenever you choose.

"What's that supposed to mean?" and "What do you mean by that?" are not exactly the same in terms of meaning, although they convey a similar intent to seek clarification.

"What do you mean by that?" is asking for an explanation of a particular statement or idea. It is used when someone wants further understanding or more information about something that was previously mentioned or said.

On the other hand, "What's that supposed to mean?" usually carries a tone of skepticism or disagreement. It implies that the speaker does not fully understand the speaker's intent or finds it questionable, and is looking for further explanation or clarification in a slightly confrontational or challenging manner.

To summarize, "What do you mean by that?" is a neutral question seeking clarification, while "What's that supposed to mean?" suggests doubt or disagreement along with the desire for a more detailed explanation.