Our daily life is surrounded by math and therefore we use functions which is a sub topic of math so much. In mathematics, function is an expression, rule, or law that defines a relationship between one variable (the independent variable) and another variable (the dependent variable).Functions are used for finding the temperature of the environment, fuel efficiency of cars, basic economics such as monthly salary or income taxes. Functions help people to finish their daily life routines easily. For example, taxi drivers use functions all the time while calculating the money that the customer should pay. For example 0.9x+13 is a function of the money that is required related to kilometers. As it is seen we use functions in so many fields even in traffic.