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Shivendra I do not know what the issue is on your Samsung Galaxy J7 Prime.
Here are some things you might do to get it to run on your device. The app runs fine on most devices so it would be interesting to note what is different about your Samsung.
1) It might not use the 'standard' Google Speech Recognition engine. This Samsung device may have its own speech recognition engine .
When you press the ASK button, do you see

a screen something like this? If not, TalkingCalculator is not finding the Google Speech Recognizer.
2) If you do see that screen, do you speak in English? and is your phone set for English or Hindi? It's gotta be set to English. If you do not see
the Speech icon, then it is probably that the App Inventor 2 SR component is incompatible with that device , especially if you do not see that screen or
the error message appears as soon as TalkingCalculator is installed.
3) It is possible your phone does not have a TextToSpeech app enabled . The app needs a text-to-speech engine (it can be download it from Google Play). The TTS language
and your device language have to be the same. The lack of a TTS could be the reason the error message does indicate
RECOGNIZE_SPEECH, not Speech Recognizer. The presence of the TTS could be the issue. You could delete the TTS component. The TTS is used to have the device speak the math answer.

and delete the two occurrences of this block , rerun the modified code and try again.

Alternatively you could download Google's Text to Speech engine from the Playstore (because it might not be installed on your device).
4)Something else is causing issues. In the aia, the Screen Sizing is set to Fixed ... perhaps change that to Responsive. That should not be an issue but it might
be a contributing factor.
Is any of this helpful? Did you get TalkingCalculator running?
Regards,
Steve