Multiply fractions with common denominators quiz. Fractions with common denominators mean that the denominators have the same numerical value. In spite of this common value, the procedure used for multiply is the same like that used in multiplying any other fraction value. In case there are any values that have similar factors, they could be reduced either before or after the operation has been carried. Learn how to multiply fractions and improve 3rd, 4th, 5th and 6th grade math skills.