Add, subtract, multiply or divide two fractions. The result is shown as a fraction, a decimal number and an unreduced fraction.
To add or subtract fractions, they need a common denominator — meaning the numbers below the fraction line must be equal. The simplest way to find a common denominator is to multiply the two denominators together, and multiply each numerator by the same number the denominator was multiplied by:
For multiplication you simply multiply numerator by numerator and denominator by denominator — no common denominator needed. For division, flip the second fraction (swap numerator and denominator) and multiply instead of dividing.
The simplest method is to multiply the two denominators together — this always gives you a common denominator that works, even though it isn't always the smallest possible one. Remember to multiply the numerator of each fraction by the same number its denominator was multiplied by.
Dividing by a fraction is the same as multiplying by its reciprocal (inverse) value. That's why you flip the second fraction upside down and multiply instead of dividing — it gives the same result, but is easier to calculate.
Simplifying a fraction means dividing the numerator and denominator by the same number, so the fraction is as simple as possible without changing its value. For example, 10/12 simplifies to 5/6 by dividing both numbers by 2.