Fractions and decimals are two ways of writing the same value, and being able to move between them quickly is a core skill for everything from measurements to percentages.
Fraction to Decimal
To convert a fraction to a decimal, divide the numerator by the denominator. For 3/4, that's 3 ÷ 4 = 0.75. This works for any fraction, and it's exactly what happens behind the scenes when this calculator shows a decimal result.
Decimal to Fraction
To go the other way, write the decimal digits over a power of 10 matching the number of decimal places, then simplify. For 0.75, that's 75/100, which simplifies to 3/4. Try it yourself with the Decimal Calculator, which shows the equivalent fraction for any decimal input.
A Note on Repeating Decimals
Some fractions, like 1/3, produce repeating decimals (0.333...) that never terminate. These can still be converted back to an exact fraction using algebra, but as a practical matter it's usually easier to keep the original fraction form when the decimal doesn't terminate cleanly.