Numbers
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Change object transparency in Numbers on iPad
You can create interesting effects by making objects more or less opaque. When you put a low-opacity object on top of another object, for example, the bottom object shows through.
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Tap to select an image, shape, text box, line, arrow, drawing, 3D object or video, or select multiple objects.
Tap
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For a drawing, tap Drawing, then drag the Opacity slider. For any other item, tap Style, then drag the Opacity slider.
You can also tap the field next to the slider and enter a new value.