Definition
Like denominators
Fractions have like denominators when their denominator numbers are the same.
What it means
In 3/8 and 5/8, both fractions are built from eighths. Because the pieces have the same name and size for the same whole, you can compare the numerators directly. For addition or subtraction, combine the counted eighths and keep the denominator.
Remember it
Same denominator means the same named fraction pieces—when the whole is the same.
Example
2/7 + 4/7 = 6/7. Both fractions count sevenths, so add 2 + 4 and keep the 7.
Watch for
Matching denominator numerals do not guarantee equal physical amounts if the wholes are different sizes.
Common mix-up
“Like denominators” describes fractions that already have the same denominator; a common denominator may be created to rewrite fractions.
Exact meaning
Like denominators are equal denominator values in two or more fractions. When the fractions refer to the same whole, those denominators name the same-sized fractional unit, such as eighths.