CPEA Mathematics

1. How to Divide a Whole Number by a
Fraction
When dividing a whole number by a fraction, you are finding how many groups of the
fraction you can fit in the whole. The standard way of dividing a whole number by a
fraction is to multiply the whole number by the reciprocal of the fraction. You can also
draw a diagram to help you visualize the process.
Method1
Multiplying by the Reciprocal
1.
1
Convert the whole number to a fraction. To do this, make the whole number the
numerator of a fraction. Make the denominator 1.[1]
 For example, if you are calculating 7÷ 3/4, you would first change 7 to 7/1.
2.

2. 2
Find the reciprocal of the divisor. The reciprocal of a number is the inverse of the
number. To find the reciprocal of a fraction, reverse the numerator and denominator.[2]
 For example, the inverse of 3/4 is 4/3.

3. 3
Multiply the two fractions. To multiply fractions, first multiply the numerators together.
Then, multiply the denominators together. The product of the two fractions equals the
quotient of your original division problem.
 For example, 7/1 × 4/3 = 28/3

4. 4
Simplify, if necessary. If you have an improper fraction (a fraction with a larger
numerator than denominator), your teacher may require you to change it to a mixed
number. Usually your teacher will require you to reduce proper fractions to lowest terms.
 For example, 28/3 simplifies to the mixed number 9 1/3.

5. Method2
Drawing a Diagram
1
Draw shapes representing the whole number. Your shape should be one capable of
dividing into equal groups, such as a square or circle. Draw the shapes large enough
that you can divide them into smaller pieces.
 For example, if you are calculating 5÷3/4, you would draw 5 circles.

6. 2
Divide each whole shape according to the fraction’s denominator. The
denominator of a fraction tells you how many pieces a whole is divided into. Divide each
whole shape into its fractional parts.
 For example, if you are dividing by 3/4, the 4 in the denominator tells you to divide each
whole shape into fourths.

7. 3
Shade in groups representing the fraction. Since you are dividing the whole number
by the fraction, you are looking to see how many groups of the fraction are in the whole
number.[5] So, first, you need to create your groups. It might be helpful to shade each
group a different color, since some groups will have pieces in two different wholes.
Leave any leftover pieces unshaded.
 For example, if you are dividing 5 by 3/4, you would color 3 quarters a different color for
each group. Note that many groups will contain 2 quarters in one whole, and 1 quarter
in another whole.

8. 4
Count the number of whole groups. This will give you the whole number of your
answer.
 For example, you should have created 6 groups of 3/4 among your 5 circles.

9. 5
Interpret leftover pieces. Compare the number of pieces you have left over to a
complete group. The fraction of a group that you have left over will indicate the fraction
of your answer. Make sure you do not compare the number of pieces you have to a
whole shape, as this will give you the wrong fraction.
 For example, after dividing the 5 shapes into groups of 3/4, you have 2 quarters,
or 2/4 left. Since a whole group is 3 pieces, and you have 2 pieces, your fraction is 2/3.

10. 6
Write the answer. Combine your whole number of groups with your fractional number
of groups to find the quotient of your original division problem.
 For example, 5 ÷ ¾ = 6 2/3

11. Method3
Solving Sample Problems
1
Solve this math problem: How many times does 1/2 go into 8?
 Since the problem is asking how many groups of 1/2 are in 8, the problem is one of
division.
 Turn 8 into a fraction by placing it over 1: 8 = 8/1.
 Find the reciprocal of the fraction by reversing the numerator and denominator:
becomes 1/2.
 Multiply the two fractions together: 8/1 × 2/1 = 16/1.
 Simplify, if necessary: 16/1 = 16.

12. 2
Solve the following problem: 16 ÷ 5/8.
 Convert 16 into a fraction by placing it over 1: 16 = 16/1.
 Take the fraction’s reciprocal by reversing the numerator and denominator: 5/8
becomes 8/5.
 Multiply the two fractions together: 16/1 × 8/5 = 128/5.
 Simplify, if necessary: 128/5 = 25 3/5.

13. 3
Solve the following problem by drawing a diagram. Rufus has 9 cans of food. She
eats 2/3 of a can every day. How many days will her food last?
 Draw 9 circles representing the 9 cans.
 Since she eats 2/3 at a time, divide each circle into thirds.
 Color groups of 2/3.
 Count the number of complete groups. There should be 13.
 Interpret the leftover pieces. There is 1 piece leftover, which is 1/3. Since a whole group
is 2/3, you have half a group left over. So, your fraction is 1/2.
 Combine the number of whole groups and fractional groups to find your final answer: 9
÷ 2/3 = 13 1/2.