OnePlus
Enable the Scientific Calculator Mode auf OnePlus
The default view of the OnePlus Calculator only shows basic operations like addition, subtraction and percentages. Scientific functions such as sine, logarithm or square root are not removed, they are just tucked away in a second panel that most people never discover.
To reveal them, open Open the Calculator app ➔ Swipe upwards to open the additional features. This gesture pulls up a panel with the full scientific keyboard on top of the existing basic layout.
Rotating the phone into landscape mode has the same effect on most OxygenOS builds: the calculator automatically switches to a wide layout that shows scientific functions alongside the number pad. This is the behavior referenced when people say they need to turn the device horizontally to get the extra functions.
If the swipe gesture does not reveal anything, the calculator app itself may be outdated or replaced by a launcher-specific version. In that case, updating the Calculator app through the system app store restores the swipe-up panel.
Installing a third-party calculator app is only worth it if you need features that go beyond scientific mode, like graphing or unit conversion history.