Organic light-emitting diodes that produce white light include an anode, a hole-transporting layer disposed over the anode, a blue light-emitting layer disposed over the hole-transporting layer, an electron-transporting layer disposed over the blue light-emitting layer, and a cathode disposed over the electron-transporting layer. It relates to both therapeutic and prophylactic treatment. By enabling all of the leads to be connected at the outset with the electronic apparatus and by internally switching the connections between the leads and the various elements of the evaluation apparatus, the calibration detection system saves time and avoids error in performing a testing protocol. The system may provide a method of learning mathematics through a cognitively authentic learning experience in constructing and building numbers. The use of a planetary gear set allows minimum speeds to be in reverse and the unique geometry of the transmission allows all of the power paths to be coaxial, thereby reducing overall size and complexity of the transmission in comparison to transmissions achieving similar transmission ratio ranges.