Add and subtract fractions of the same denominator by adding the numerators -- 3/8 + 1/8 = 4/8, or 1/2.
Multiply two or more fractions by taking the products of all the numerators and all the denominators. For example, 1/3 * 2/3 = 2/9.
Divide fractions by multiplying the numerator by the reciprocal of the denominator. The reciprocal of a fraction is the denominator divided by the numerator. For example, (1/2)/(2/3) = 1/2 * 3/2, or 3/4.
Add or subtract fractions with different denominators by converting the fractions to equal denominators. Determine the least common multiple of the denominators then multiply both parts of each fraction to change it. For example, 3/5 and 4/15 have a least common multiple of 15, so multiply both parts of 3/5 by 3 to convert the fraction to 9/15. Then add or subtract the numerators.
Simplify fractions by dividing the numerator and denominator by their greatest common factor. 4/6 has a greatest common factor of 2. Divide both by 2 to get 2/3.