🇺🇸 CCSS Math · Grade 5

5.NF.B.3: Fractions as division

5.NF.B.3 explained: a/b means a ÷ b, sharing problems with fraction and mixed-number answers, misconceptions, a worked example and practice.

Common Core standard CCSS.Math.Content.5.NF.B.3

Interpret a fraction as division of the numerator by the denominator (a/b = a ÷ b). Solve word problems involving division of whole numbers leading to answers in the form of fractions or mixed numbers, e.g., by using visual fraction models or equations to represent the problem. For example, interpret 3/4 as the result of dividing 3 by 4, noting that 3/4 multiplied by 4 equals 3, and that when 3 wholes are shared equally among 4 people each person has a share of size 3/4. If 9 people want to share a 50-pound sack of rice equally by weight, how many pounds of rice should each person get? Between what two whole numbers does your answer lie?

Grade
Grade 5
Domain
Number & Operations - Fractions (NF)
Cluster
Apply and extend previous understandings of multiplication and division

Official wording from the Common Core State Standards for Mathematics (© 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers). View on thecorestandards.org

What 5.NF.B.3 means

The fraction bar is also a division sign. Fifth graders learn that 3/4 can be read as 3 ÷ 4: if 3 pizzas are shared equally among 4 people, each person gets 3/4 of a pizza. One way to see it is to cut each of the 3 pizzas into fourths, giving 12 fourths, and hand out 3 fourths to each person.

This idea turns division problems with remainders into problems with exact fraction answers. If 9 people share a 50-pound sack of rice equally, each gets 50 ÷ 9 = 50/9 pounds, which is 5 5/9 pounds, a value between 5 and 6. Students solve such word problems with visual fraction models or equations and should be able to explain both views: a/b as a parts of size 1/b, and a/b as the size of one share when a wholes are split among b people. Checking with multiplication (3/4 × 4 = 3) ties the two together.

Students should be able to

  • Explain why a/b is equal to a ÷ b using a sharing story or model.
  • Write a division expression as a fraction and a fraction as a division expression.
  • Solve sharing word problems whose answers are fractions or mixed numbers.
  • Identify the two whole numbers that a fraction or mixed-number answer lies between.
  • Check a fractional quotient by multiplying it by the divisor.

Common misconceptions

Dividing the larger number by the smaller

When 3 cookies are shared by 4 children, students sometimes compute 4 ÷ 3. The amount being shared is divided by the number of people: 3 ÷ 4 = 3/4.

Treating the remainder as the fraction's numerator only

50 ÷ 9 = 5 remainder 5 becomes 5 5/9, not 5.5 or 5 5/10. The remainder is shared among 9, so it is 5 ninths.

Believing division always gives a whole number

Students used to remainders may say 2 ÷ 5 'can't be done'. Sharing 2 sandwiches among 5 people clearly gives each person 2/5 of a sandwich.

Separating the two meanings

Some students accept 3/4 as 'three of four parts' but not as 3 ÷ 4. Showing both with the same drawing links them.

Worked example: sharing rice

9 people share a 50-pound sack of rice equally by weight. How many pounds does each person get? Between which two whole numbers is the answer?

  1. Each share is 50 ÷ 9 pounds, which can be written as the fraction 50/9.
  2. 9 × 5 = 45, so 50/9 contains 5 wholes with 50 - 45 = 5 ninths left over.
  3. So 50/9 = 5 5/9 pounds.
  4. The answer lies between 5 and 6 pounds. Check: 9 × 5 5/9 = 45 + 5 = 50.

Answer: Each person gets 50/9 = 5 5/9 pounds of rice, between 5 and 6 pounds.

Teaching 5.NF.B.3

Act out sharing with paper circles: 2 'pizzas' shared by 3 students. Students cut, distribute and name the share. Recording 2 ÷ 3 = 2/3 beside the drawing makes the equivalence memorable.

Expect word problems about sharing money, food or lengths, items asking which expression equals a fraction, and questions asking between which two whole numbers an answer falls.

6 practice questions

Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.

Score: 0 / 6(0 of 6 checked)
  1. 1.

    Write 7 ÷ 8 as a fraction.

    Answer and explanation

    Answer: 7/8

    a ÷ b = a/b, so 7 ÷ 8 = 7/8.

  2. 2.

    4 friends share 3 granola bars equally. How much does each friend get?

    Question 2 options
    Answer and explanation

    Answer: B) 3/4 of a bar

    The amount shared, 3 bars, is divided by the number of friends, 4: 3 ÷ 4 = 3/4 of a bar each.

  3. 3.

    A 22-foot rope is cut into 5 equal pieces. How long is each piece? Give a mixed number.

    Answer and explanation

    Answer: 4 2/5 (also accepted: 4 2/5 feet, 22/5)

    22 ÷ 5 = 22/5. 5 × 4 = 20, leaving 2, so each piece is 4 2/5 feet.

  4. 4.

    Between which two whole numbers does 41 ÷ 6 lie?

    Question 4 options
    Answer and explanation

    Answer: D) 6 and 7

    6 × 6 = 36 and 6 × 7 = 42. 41 is between 36 and 42, so 41 ÷ 6 = 6 5/6, between 6 and 7.

  5. 5.

    Which whole number divided by 3 gives the fraction 8/3?

    Answer and explanation

    Answer: 8

    8/3 means 8 ÷ 3, so the whole number is 8.

  6. 6.

    Why does 2/5 × 5 equal 2?

    Question 6 options
    Answer and explanation

    Answer: B) Because 2/5 is the share when 2 is divided into 5 equal parts, and 5 of those shares make 2

    2/5 = 2 ÷ 5. Five equal shares of size 2/5 put back together give the original 2.

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FAQ

Why is 5.NF.B.3 important?

It connects fractions and division, so remainders can be expressed exactly as fractions. This underpins fraction division in sixth grade and ratios such as unit rates.

Should answers be written as fractions or mixed numbers?

Both are correct. Word problems often read better as mixed numbers, such as 5 5/9 pounds, and asking where the answer lies between two whole numbers encourages that form.

More grade 5 Number & Operations - Fractions standards

5.NF.A.1: Adding and subtracting unlike fractions5.NF.A.2: Fraction word problems and estimation5.NF.B.4: Multiplying fractions5.NF.B.5: Multiplication as scaling5.NF.B.6: Real-world fraction multiplication5.NF.B.7: Dividing unit fractions and whole numbers
All Grade 5 math standards →Standards home →