large area can be provided with a floor in particular dance floor or sports floor each panel 1 is basically rectangular in fact being cut from a rectangular blank of 2 1 proportions whose outline is shown at 13 and is of a shape symmetrical to a longitudinal center axis a l and to a transverse center axis a t the straight outer edges of the panel are formed with notches 6 11 and 11 u2032 and teeth 9 10 and 10 u2032 more particularly one long side of each panel 1 up in fig3 has two identical trapezoidal or keystone shaped notches 6 separated by a short tooth 10 and flanked by two teeth 10 u2032 each half the width of the center tooth 10 and the opposite long edge is formed with a central notch 11 complementary to the tooth 10 and flanked by two of the full width teeth 9 complementary to the notches 6 and themselves flanked by two notches 11 u2032 each half the width of the center notch 11 one short end edge to the left in fig3 has a central full width tooth 9 of the same size as the notches 6 flanked by two half width notches 11 u2032 and the opposite short end edge has a central full width notch 6 flanked by two half width teeth 10 u2032 thus it is possible for the panels to fit together with their long and short edges aligned as shown in fig4 and theoretically it is also possible to stagger the panels 1 with every other row having its short end edges in the middle of.