To navigate between sheets, use the sheet navigation panel below the current worksheet. Tap the necessary sheet tab to switch to the sheet.
You can also use the List view to easily navigate through the sheets. To do this, tap the 
List view button and select the needed sheet from the list. The selected sheet will be opened. This option may come in handy when the book contains a lot of sheets.
To scroll a sheet, swipe up or down, left or right.
To zoom in a sheet, use the stretch gesture: place two fingers on the screen and move them apart.
To zoom out a sheet, use the pinch gesture: place two fingers on the screen and move them together.