Fractions · Grades 4, 5

Mixed Numbers and Improper Fractions: Converting Both Ways

Quick answer

An improper fraction has a top number bigger than its bottom number, like seven quarters. A mixed number writes the same amount as a whole number plus a fraction, like one and three quarters. To go from improper to mixed, divide the top by the bottom: the quotient is the whole number and the remainder becomes the new top. To go back, multiply the whole number by the bottom and add the top.

What you'll learn

  • Change an improper fraction into a mixed number
  • Change a mixed number into an improper fraction
  • Choose the form that suits the job in front of you

Two ways to write the same amount

Look at where 74\tfrac{7}{4} sits.

Seven quarters is one whole and three quarters A number line from 0 to 2 divided into quarters. A dot sits three ticks past 1, labelled seven quarters. 0 1 2 74
Seven quarters is one whole and three quarters

The dot is past 11 but not yet at 22. Counting from 00, four quarters got you to 11, and three more carried you along.

So the same spot has two names:

74=134\frac{7}{4} = 1\tfrac{3}{4}
  • 74\tfrac{7}{4} is an improper fraction: the top number is bigger than the bottom.
  • 1341\tfrac{3}{4} is a mixed number: a whole number next to a fraction.

The word improper is unfortunate. There is nothing wrong with 74\tfrac{7}{4}.

Improper to mixed: divide

The bottom number tells you how many parts make one whole. So ask how many whole groups fit.

For 74\tfrac{7}{4}, ask how many 44s fit into 77.

7÷4=1 remainder 37 \div 4 = 1 \text{ remainder } 3
  • The quotient 11 is the number of wholes.
  • The remainder 33 is the parts left over.
  • The bottom number never changes.
74=134\frac{7}{4} = 1\tfrac{3}{4}

Mixed to improper: multiply, then add

Go the other way by asking how many parts there are in total.

For 2132\tfrac{1}{3}: each whole is 33 thirds, and there are 22 wholes, so that is 2×3=62 \times 3 = 6 thirds. Add the extra 11 third.

213=2×3+13=732\tfrac{1}{3} = \frac{2 \times 3 + 1}{3} = \frac{7}{3}

Why the multiply-then-add rule works

It is not a trick. It is addition written out.

213=2+132\tfrac{1}{3} = 2 + \frac{1}{3}

Rewrite the 22 as thirds, since 1=331 = \tfrac{3}{3}:

2=632 = \frac{6}{3}

Now both parts are thirds, so they add directly:

63+13=73\frac{6}{3} + \frac{1}{3} = \frac{7}{3}

The 66 came from 2×32 \times 3, and the 11 was already there. That is exactly “multiply the whole by the bottom, then add the top”.

Which form should you use?

JobBetter form
picturing an amountmixed number
measuring with a cup or rulermixed number
multiplying or dividingimproper fraction
comparing two amountseither, once the bottom numbers match

Most calculations convert to improper form first, do the work, then convert back at the end. A mixed number is a sum in disguise, and sums are awkward to multiply.

Worked examples

Common mistakes

Practice problems

  1. Write 92\tfrac{9}{2} as a mixed number.

    Hint

    How many 22s fit into 99, and what is left?

    Answer

    4124\tfrac{1}{2}

    Full solution

    9÷2=49 \div 2 = 4 remainder 11, so the answer is 4124\tfrac{1}{2}.

  2. Write 175\tfrac{17}{5} as a mixed number.

    Answer

    3253\tfrac{2}{5}

    Full solution

    17÷5=317 \div 5 = 3 remainder 22, so the answer is 3253\tfrac{2}{5}.

  3. Write 2342\tfrac{3}{4} as an improper fraction.

    Answer

    114\tfrac{11}{4}

    Full solution

    2×4=82 \times 4 = 8, then 8+3=118 + 3 = 11. The answer is 114\tfrac{11}{4}.

  4. Write 5165\tfrac{1}{6} as an improper fraction.

    Answer

    316\tfrac{31}{6}

    Full solution

    5×6=305 \times 6 = 30, then 30+1=3130 + 1 = 31. The answer is 316\tfrac{31}{6}.

  5. Write 205\tfrac{20}{5} as a mixed number or whole number.

    Answer

    44

    Full solution

    20÷5=420 \div 5 = 4 remainder 00, so there is no fraction part. The answer is the whole number 44.

  6. Write 268\tfrac{26}{8} as a mixed number in simplest form.

    Hint

    Convert first, then simplify the leftover fraction.

    Answer

    3143\tfrac{1}{4}

    Full solution

    26÷8=326 \div 8 = 3 remainder 22, giving 3283\tfrac{2}{8}.

    Divide both parts of 28\tfrac{2}{8} by 22 to get 14\tfrac{1}{4}, so the answer is 3143\tfrac{1}{4}.

  7. Which is bigger, 134\tfrac{13}{4} or 3123\tfrac{1}{2}?

    Hint

    Put both in the same form first.

    Answer

    3123\tfrac{1}{2}

    Full solution

    134=314\tfrac{13}{4} = 3\tfrac{1}{4}, and 14\tfrac{1}{4} is less than 12\tfrac{1}{2}.

    So 3123\tfrac{1}{2} is bigger.

  8. A recipe calls for 94\tfrac{9}{4} cups of flour. Your cup is marked in quarters. How would you say that amount out loud?

    Answer

    Two and a quarter cups.

    Full solution

    9÷4=29 \div 4 = 2 remainder 11, so 94=214\tfrac{9}{4} = 2\tfrac{1}{4}.

    Fill the cup twice, then once more to the quarter mark.

  9. Nina writes 327=573\tfrac{2}{7} = \tfrac{5}{7}, because she added 33 and 22. What went wrong?

    Hint

    Is 57\tfrac{5}{7} bigger or smaller than 11?

    Answer

    She added the whole number to the top instead of multiplying first. The answer is 237\tfrac{23}{7}.

    Full solution

    Each whole is 77\tfrac{7}{7}, so three wholes are 3×7=213 \times 7 = 21 sevenths. Adding the extra 22 gives 237\tfrac{23}{7}.

    Her answer 57\tfrac{5}{7} is less than one whole, which cannot be right for a number that starts with a 33.

  10. Write a mixed number and an improper fraction for the amount three eighths past 44.

    Answer

    4384\tfrac{3}{8}, which is 358\tfrac{35}{8}.

    Full solution

    The mixed number is 4384\tfrac{3}{8}.

    Converting: 4×8=324 \times 8 = 32, then 32+3=3532 + 3 = 35, so the improper fraction is 358\tfrac{35}{8}.

Frequently asked questions

What is an improper fraction?

It is a fraction whose top number is bigger than or equal to its bottom number, like seven quarters. Nothing is wrong with it. It names an amount of one whole or more.

How do I turn an improper fraction into a mixed number?

Divide the top number by the bottom number. The whole-number part of the answer goes in front, and the remainder becomes the new top number over the same bottom number.

How do I turn a mixed number into an improper fraction?

Multiply the whole number by the bottom number, then add the top number. That total goes over the same bottom number. Two and one third becomes seven thirds.

Which form should I use?

Mixed numbers are easier to picture and to measure with. Improper fractions are easier to multiply and divide with, so most calculations start by converting to improper form.

What to learn next

Key terms in this lesson

Quotient
The quotient is the answer to a division. In 12 ÷ 4 = 3, the 12 is the dividend, the 4 is the divisor, and the 3 is the quotient.

Standards alignment

This lesson covers the following Common Core State Standards for Mathematics.

  • CCSS.MATH.CONTENT.4.NF.B.3Number and Operations—FractionsUnderstand a fraction a/b with a > 1 as a sum of fractions 1/b.
  • CCSS.MATH.CONTENT.4.NF.B.3bNumber and Operations—FractionsDecompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions, e.g., by using a visual fraction model.
  • CCSS.MATH.CONTENT.4.NF.B.3cNumber and Operations—FractionsAdd and subtract mixed numbers with like denominators, e.g., by replacing each mixed number with an equivalent fraction, and/or by using properties of operations and the relationship between addition and subtraction.