After the release of the iPhone X, which introduced the notch -- the black bar at the top of your device that houses a speaker and camera -- there wasn't enough screen real estate left to keep the battery percentage up there, so Apple nixed the feature from iOS.
You can view the battery percentage in the Control Center.
Sure, you can swipe down from the top right of your iPhone to view the exact percentage in the Control Center, but it just isn't the same.
And it's nearly impossible to gauge the exact percentage from just the battery icon, which is not good if your iPhone is close to dying.
If you toggle the Battery Percentage feature off, you'll remove the numbers from the status bar and revert back to the old battery icon design
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