小数から分数への変換計算機
任意の小数を約分された分数に変換します。ステップバイステップのプロセスを表示。
変換方法 a Decimal to a Fraction
To convert a decimal to a fraction:
- Count the decimal places (e.g., 0.75 has 2 decimal places)
- Write the decimal as a fraction over 10^n (e.g., 75/100)
- Simplify using the Greatest Common Divisor (GCD) → 75/100 = 3/4
Our calculator does all three steps automatically and shows the result in lowest terms.
Common Decimal to Fraction Equivalents
| Decimal | Fraction |
|---|---|
| 0.1 | 1/10 |
| 0.125 | 1/8 |
| 0.25 | 1/4 |
| 0.333... | 1/3 |
| 0.5 | 1/2 |
| 0.666... | 2/3 |
| 0.75 | 3/4 |
| 0.875 | 7/8 |
とは the GCD?
The Greatest Common Divisor (GCD) is the largest number that divides both the numerator and denominator without remainder. Dividing both by the GCD simplifies the fraction to its lowest terms.
For example, GCD(75, 100) = 25. So 75/100 ÷ 25/25 = 3/4. The Euclidean algorithm is the standard efficient method: GCD(a, b) = GCD(b, a mod b) until b = 0.
よくある質問
How do I convert a repeating decimal to a fraction?
For a repeating decimal like 0.333..., set x = 0.333..., then 10x = 3.333..., subtract: 9x = 3, so x = 3/9 = 1/3. For 0.142857142857... (repeating 6 digits), the process requires multiplying by 10^6.
とは the fraction for 0.625?
0.625 = 625/1000. GCD(625, 1000) = 125. So 625/1000 ÷ 125/125 = 5/8. Therefore 0.625 = 5/8.
Can all decimals be expressed as fractions?
Terminating decimals (like 0.75) and repeating decimals (like 0.333...) can always be written as fractions. Non-repeating, non-terminating decimals (like π = 3.14159...) are irrational and cannot be expressed as exact fractions.