To work out the amount you need simply reduce your dimensions in to powers of ten so:-
45 cm X 63 cm becomes 4.5 X 6.3
now multiply your two numbers and round up so as an example:-
4.5 X 6.3 = 28.35 = 29 units to buy
MDF is an incredibly versatile interior panel, with a high internal bond strength, used extensively throughout the construction and furniture industries. It has a smooth surface that is ideal for painting, it can be worked easily with all conventional woodworking machines, saws cleanly and drills easily. A full board measures 122.2cm X 244.4cm and purchases will be cut down from these dimensions.