Fractions can represent parts of a whole or multiple units, written as a numerator over a denominator. Equivalent fractions have equal values and can be obtained by multiplying or dividing the numerator and denominator by the same number. To calculate a fraction of a quantity, multiply the quantity by the numerator and divide by the denominator. To add or subtract fractions, find a common denominator and then add or subtract the numerators. To multiply fractions, multiply the numerators and denominators, while to divide fractions invert the divisor and multiply the fractions.