🍕 Fractions 📚 Grade 4 ⏱ 6 min
Adding and Subtracting Fractions: Same Denominator
When denominators match, adding and subtracting fractions works almost as simply as with regular numbers.
Add only the numerators
1/5+2/5=3/5. The denominator stays the same (splitting into the same-size parts), only the numerators — the part count — get added.
💡 Anchor: one pizza cut into 5 slices. First ate 1 slice, then 2 more — ate 3 slices out of 5 total, or 3/5.
Subtraction works the same way
4/7−2/7=2/7. Subtract the numerators, leave the denominator alone.
FAQ
Why can't the denominators be added too?
The denominator shows the size of the parts, not their count — part size does not change just because the count changed.