What best describes a real number?

A real number is best described as a rational or irrational number. This encompasses all numbers that can be found on the number line, including integers, whole numbers, fractions, decimals, and numbers that cannot be expressed as fractions, such as square roots of non-perfect squares and π (pi).

Rational numbers are those that can be expressed as a fraction of two integers, where the denominator is not zero. For example, 1/2 and 7 are both rational numbers. On the other hand, irrational numbers cannot be expressed as a simple fraction, which includes numbers like √2 and π. Since the definition of real numbers includes both of these categories, it provides a comprehensive understanding of what constitutes real numbers. This thorough categorization is vital for studying mathematics, as real numbers are foundational to calculus, algebra, and many other areas.