answer:
so the basic formula to find volume in shapes would be length × width × height.
here is a example : ( i cant really make the shape 3D so lets just say it is )
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| | 3
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5
and because i cant make the shape 3D, the width will be 2
all you really need to do is multiply all of them together, for smaller numbers you shouldn't have to really use your calculator ( if you have a pretty good memory of your times tables then you shouldn't have to as least ) but with bigger numbers then i would recommend using your calculator if your teacher does lets you
5 * 3 * 2
= 30 units !
i hope this helps you and if you have anymore questions then please let me know! :)