To calculate the magnification of a telescope, you need to know the focal length of the telescope and the focal length of the eyepiece being used.
You can use the following formula: Magnification = Telescope Focal Length / Eyepiece Focal Length, for example, if the focal length of your telescope is 1000mm and the focal length of your eyepiece is 20mm, then your magnification would be: Magnification = 1000mm / 20mm = 50x
This means that the image you see through the telescope will appear 50 times closer than it would with the naked eye.
It is important to note that magnification alone does not determine the quality or performance of a telescope. Other factors such as aperture size and optical quality also play important roles in determining the image quality and clarity of the telescope.
Please ask a member of the Focalpoint team if you are unsure and the following video from Celestron explains the formula in an easy-to-understand way.