循環小数

1. Origins, structure, and basic meaning

• Structure: 循環小数(じゅんかんしょうすう) is a decimal in which a fixed digit or sequence repeats indefinitely from some position after the decimal point.
• Basic usage: It is used when expressing fractions as decimals or marking the recurring part.
  • The one-third in the example is written 0.333…, with 3 repeating.

2. Common pitfalls and similar expressions

• The repeating part
  • The recurring part can be one digit or a sequence of digits.
  • In 0.121212…, the repeating sequence is 12.
• The mathematical term 小数
  • 小数(しょうすう) means a decimal, whereas 少数(しょうすう) means a small number.