Some hardware & what are their uses

7-digit 7-segment LED display + LED light

  ~ for displaying information to users

  ~ more compact than 7 separate LED  display

  ~ only uses 14 pins

16x Tactile Push Button 

  ~ for the keypad

  ~ using 4X4 small tactile push buttons instead of a whole keypad

USB mini 

  ~ input program into PCB

ATMEGA32U4

  ~ to run program 

  ~ store memory