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Add, subtract, multiply, and divide fractions. Simplify results, convert between fractions, decimals, and percentages — all with exact arithmetic.
Fraction A
Operator
Fraction B
Result
Decimal
0
Percentage
0%
Step-by-step solution
0/1 + 0/1
= 0/1 — same denominator, add numerators
Quick Reference — Common Fractions
| Fraction | Decimal | Percentage |
|---|---|---|
| 12 | 0.5 | 50% |
| 13 | 0.333... | 33.33% |
| 23 | 0.667... | 66.67% |
| 14 | 0.25 | 25% |
| 34 | 0.75 | 75% |
| 15 | 0.2 | 20% |
| 18 | 0.125 | 12.5% |
| 110 | 0.1 | 10% |
| 116 | 0.0625 | 6.25% |
Click any row to load it into the calculator.
How fractions work
A fraction represents a part of a whole. The top number (numerator) tells you how many parts you have; the bottom number (denominator) tells you how many equal parts make the whole. A proper fraction has a numerator smaller than the denominator (e.g. 3/4). An improper fraction has a larger numerator (e.g. 7/4). A mixed number combines a whole number with a fraction (e.g. 1 3/4).
Simplifying fractions
To simplify a fraction, find the Greatest Common Divisor (GCD) of the numerator and denominator, then divide both by it. For example, 12/18: GCD(12, 18) = 6, so 12/18 = 2/3. A fraction is fully simplified when the numerator and denominator share no common factors other than 1.
Adding fractions
To add or subtract fractions, first find a common denominator (the Least Common Multiple of the two denominators). Convert both fractions to this common denominator, then add or subtract the numerators. Finally, simplify the result if possible.
Fractions in real life
Cooking & baking
Recipes call for 1/2 cup, 3/4 teaspoon, or 1/3 of a packet. Doubling or halving a recipe means multiplying or dividing fractions.
Construction & DIY
Measurements in inches often use fractions — 3/4 inch plywood, 5/8 inch drywall, or cutting a board into thirds.
Finance & discounts
A 1/3 off sale, splitting a bill into quarters, or calculating that you've paid 7/12 of your annual insurance.
The formulas
Addition:
a/b + c/d = (ad + bc) / bd
Subtraction:
a/b − c/d = (ad − bc) / bd
Multiplication:
a/b × c/d = ac / bd
Division:
a/b ÷ c/d = ad / bc
Adding fractions requires a common denominator. Find the Least Common Multiple (LCM) of the two denominators, convert each fraction so both share that denominator, then add or subtract the numerators. For example, 1/3 + 1/4: the LCM of 3 and 4 is 12, so 1/3 = 4/12 and 1/4 = 3/12. Adding gives 7/12. For mixed numbers, first convert to improper fractions, perform the operation, then convert back.
To convert a fraction to a decimal, simply divide the numerator by the denominator. For example, 3/8 = 3 ÷ 8 = 0.375. Some fractions produce repeating decimals — 1/3 = 0.333... and 2/7 = 0.285714285714... To convert a decimal back to a fraction, write it over a power of 10 (e.g. 0.75 = 75/100) and simplify by dividing both by the GCD (25), giving 3/4.