The calculator is a built-in app of the system. After being deleted, you can recover it by the following methods:
realme UI 4.0 & above versions: Settings > Apps > Recover System Apps.
realme UI 3.0: Settings > Apps > Recover Uninstalled System Apps.
realme UI 2.0: Settings > App Management > Recover Uninstalled System Apps.
realme UI R & Go & T & S & U Edition: Not supported
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