What is a Decimal Expansion?

A decimal expansion represents a real number in base-10 positional notation. Every number can be written as an integer part followed by a decimal point and a sequence of digits representing fractions of powers of ten.

• Terminating decimals: Rational numbers like 1/4 = 0.25 eventually end after a finite number of digits. Only fractions whose denominator has only prime factors 2 and 5 terminate.
• Repeating decimals: Some rational numbers like 1/3 = 0.333... have a repeating pattern that continues forever.
• Non-repeating, non-terminating: Irrational numbers like π and √2 have decimal expansions that continue infinitely without any repeating pattern.

This tool lets you explore these expansions by calculating the first N decimal digits of any expression. Use built-in constants like pi, sqrt(2), e, or enter your own arithmetic expressions.

Learn more on Wikipedia .