Elementary arithmetic is a branch of mathematics that deals with basic numerical operations such as addition, subtraction, multiplication, and division. It is a fundamental subject that forms the basis for more advanced mathematical concepts. Due to its low level of abstraction, elementary arithmetic is the most universally taught branch of mathematics. Digits Digits are the symbols used to represent the values of numbers in a numeral system. The most commonly used digits are the Western-style Arabic numerals (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), which are used in the Hindu-Arabic numeral system. The Hindu–Arabic numeral system is a positional notation system that is used to represent numbers using these digits. In a positional notation system, the value of a digit is determined by its position in the number, with the value of the digit increasing as its position becomes more significant. In this type of system, the increase in value of an additional digit includes one or more multiplications with the Radix value and the result is added to the value of an adjacent digit. For example, in the numeral "123," the digit "1" has a value of one hundred (1 × 100), the digit "2" has a value of two tens (2 × 10), and the digit "3" has a value of three ones (3 × 1). The Hindu-Arabic numeral system is used worldwide and is the standard way of representing numbers in most countries. In elementary arithmetic, students typically learn to understand the values of individual whole numbers represented using Arabic numerals with a maximum of seven digits and to perform basic operations such as addition, subtraction, multiplication, and division using Arabic numerals with a maximum of four digits per number. These concepts form the foundation for more advanced mathematical principles and are essential in everyday life. Understanding and being able to perform these operations is necessary for success in math and is a fundamental part of elementary arithmetic. Successor function and size In elementary arithmetic, the successor of a natural number (including zero) is the result obtained by adding 1 to that number, while the predecessor of a natural number (excluding zero) is the result obtained by subtracting 1 from that number. For example, the successor of zero is one and the predecessor of eleven is ten, or, in mathematical terms: and . Every natural number has a successor, and all natural numbers (except