Arithmetic is one of the many branches of mathematics dealing only with numbers and the basic operations performed on these numbers.
These basic operations are addition, subtraction, multiplication, and division.
Arithmetic is the math students learn in pre-school and elementary school.
Arithmetic does not deal with variables.
Arithmetic forms the foundation for more advanced branches of mathematics, including pre-algebra, algebra, calculus, number theory, and so forth...
Adding two numbers together to find the sum is an example of arithmetic.
8 + 2 = 10
In this example, we are performing addition and addition is one of the basic arithmetic operations. We take the numbers 8 and 2, and by applying the addition operator (+), we find that the sum is 10.
Of course arithmetic can be as complicated as doing long division such as when you try to divide 578548 by 365 for example.