Sometimes you need a specific angle like 90°. The most common technique is to open up the Channel Box and manually enter the value.
We will take a look at an alternative using the rotate tool (E). Simply press “J” while rotating to toggle “Discrete Rotation”. This feature will force the rotate tool to snap to specific angles.
You can adjust the default behavior in the Tool Settings (Window > Setting and Preferences > Tool Settings) of the Rotate Tool.