Where is the DONE button for numeric keypad?

When you are inputting some numbers, you will see the keypad like this , will you wonder what to do when you finish the number? Do you expect there is a “DONE button” somewhere?
how can I add it?

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Hi, I’m assuming this is on Android? There is no Done button on Android on the keyboard. I also thought this is weird, but you have to press the ‘back’ button on the Android device to close the keyboard.