Sample papers of Maths for class 8th, 9th and 10th. Is this the shortcut to crack exam?

Imagine you were preparing for a marathon. Would you be able to run 42 km without any practice? No right? You would start running long before the day of marathon and measure the distance covered in whatever time frame you set for yourself. You would start practicing long before the marathon begins so that your stamina keeps improving until the day of marathon.