Everyone has studied this rule in their childhood. It  stands for “bracket, “off”, “division”, “multiplication”, “addition”, “subtraction”. A mathematical operation involve a number of operators but they must carry out in a particular order. The circuit described here will help you to practically implement the BODMAS rule which we have studied.The circuit is made with the help of three IC’s namely 7404, 7408 and 4073. 7404 is a hex inverter or NOT gate IC. It is a 14 pin IC and contain 6 individual NOT gate on a single IC. 7408 is a quad 2 input AND gate IC. It contains 4 individual AND gate on a single IC. 4073 is a triple 3 input AND gate. It contains 3 individual AND gate on a single IC. LED, switches and resistors are  also used in this circuit. 

Tactile switches are most often found in control panels of monitors, televisions, mobiles, radios, etc. They are widely used in industry for different purposes. They come with various number of pins as per the requirement. A tactile switch has only two states ON and OFF. Here 4 pin tactile switch is discussed.Inside the switch we can see there is a hat like thing. Actually it’s the button that we tap. The button looks very similar to a hat. At the bottom of the button there is a pointing arrow and below it lies a conducting plate. The pins are attached below the plate.