Five Push button NO switches from left to right are a) FF Reset b) Key 0 c) Key 1 d) Key 2 e) Key 3. Press and hold numeric keys for few seconds to stabilize all Relays and display proper number in unit place. SR Flip Flop has been used for Key Board. D-Flip Flop "Parallel In Parallel Out" mode has been used to shift Unit place number to Ten place and Ten place to Hundred place. As it is a 2 Bit arrangement so any number in between 000 to 333 could be displayed.
