Method 1: Press the Volume Down/Up or Power button on the side of your device.
Method 2:Enable the Gesture function by going to the “Tablet” app and pressing the menu key
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Method 3: Go to menu -> “Settings” -> “Sound”-> activate “Silent mode”.
Method 4: Drag the Status Bar down with your finger and then touch the “Notification” icon to change to “Vibrate”.
Note: Press the “power” key and “volume up” key at the same time to switch to vibration mode quickly.