Transcript 6.1 Dividing Fractions by whole numbers

6.1 Dividing
Fractions by
whole numbers
Grade 8 by Rhonda Friesen
What we already know
about division…
• 6÷ 2=
• We know that division is splitting up a number into
equal size groups.
• How many groups of 2 are in 6?
Vocabulary for division
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6÷ 2=
6 is the dividend (Total number)
2 is the divisor (number of apples in each group)
3 is the quotient (number of groups)
6÷ ½ = ?
• I have six apples. I am going to share my apples
with some friends. If I give each friend ½ an apple,
how many friends can I give apples?
• I have 5 pizzas. I am going to share my pizzas with
some friends. If I give each friend 1/3 of the pizza,
how many friends will get pizza?
Using a bar model
• We have 6 cupcakes. We decide to put them
equally into 3 boxes. How many cupcakes will be in
each box?
• 6÷ 3=
6 is 3 groups
of what
number ?
• Cupcakes
If ½ a box of cupcakes can hold 6
cupcakes, how many cupcakes can the
box hold?
• 6÷ ½ = ?
• 6 is ½ of what number?
• Cupcakes
If 1/3 of a gas tank holds 5 liters of gas, how
many liters does the gas tank hold?
• 5 is 1/3 of what number?
• What is the equation?
Keith was preparing the course for a 3 mile bicycle race.
He set up water stations every ¾ mile for the bicycle
riders in the race. How many water stations did he set
up?
• What is the equation ?
• ___________________
Sabrina has 6 pizzas at her birthday party. If each person
can eat 2/3 of a pizza, how many people can she serve?
• What is the equation?
• ___________________
Dividing whole numbers and fractions without
• You know that..
models…
o 2÷ ¼ = how many groups of ¼ are in 2.
o 2÷ ¼ has the same answer as
When we are dividing by a fraction, we can get the
same answer by multiplying by the flip of the
fraction.
• 3÷ 1/5 =
Reciprocal
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The flip of a fraction is called the reciprocal
The reciprocal of ½ is ________
The reciprocal of 1/3 is ______
The reciprocal of 1/6 is ______
The reciprocal of 2/3 is _______
The reciprocal of ¾ is ________
The reciprocal of 7/9 is _______
Aliyah has 6 sticks of butter. She needs 1/3 of a
butter stick to make a dozen cookies. How many
dozens of cookies can she make?
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How many groups of 1/3 are in 6?
There are ____ groups of 1/3 are in 6.
What is your equation? _________________
SOLVE:
• Sentence: _____________________________
What happens if the
whole number is not at
the beginning of the
equation?
Three students shared 2/3 of a cake equally. What
fraction of the cake did each student receive?
• What is the equation? _______________
• 2/3 is 3 groups of what number ?
• My answer will be _____________than 2/3.
Kiah divided ¾ pounds of grapes equally with 2
children she was babysitting. What fraction of the
grapes did each child receive?
• Equation: _________________
• ¾ is 2 groups of what number?