Lesson · M.2.2

Adding and subtracting fractions

How to add and subtract fractions on the HESI A2 math subtest, with common and unlike denominators, mixed numbers, and borrowing.

ObjectiveM.2.2Read4 minExam weightFractions ≈ 20% of Mathematics

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What you will be able to do

  • Add and subtract fractions that already share a denominator.
  • Find a common denominator and add or subtract fractions that do not match.
  • Add and subtract mixed numbers, including borrowing when a fraction runs short.

What the lesson concludes

  • You can only add or subtract numerators once the denominators match.
  • A common denominator does not have to be the smallest one, but the least common denominator keeps the numbers manageable.
  • Convert mixed numbers to improper fractions, or borrow a whole as an equivalent fraction, before subtracting.
  • Always reduce the final answer and convert an improper result back to a mixed number.