copyright © ed2netlearning.inc 1 dividing fractions and whole numbers

Copyright © ed2netlearning.inc 1

Dividing Fractions and Whole numbers

Copyright ©Ed2NetLearning.Inc 2

Previous Knowledge

Multiply:1. ½ x ½ x 20 = 52. 2/3 x 2/5 = 4/153. 3/20 x 1 ¼ = 3/164. 3 1/3 x 2 ¼ = 7 ½ 5. 5 x 1 2/3 = 8 1/3


Objective

Identify and understand the term reciprocal

To understand division of fractions and whole problems

To do problems based on division


Reciprocal of a fraction

Any two numbers whose product is 1 are called reciprocals.

To find the reciprocal of a particular fraction, inter change the numerator and denominator.

For example reciprocal of 2 = 3 3 2


Practice Problems

Find the reciprocal of the following:1. 7/2 = 2/72. 4/5 = 5/43. 2/3 = 3/24. 5/6 = 6/55. 7/12 = 12/76. 5/33 = 33/57. 1/8 = 8/1 = 8


Dividing a whole number by a fraction

To divide a whole number by a fraction, » step 1: Write the whole number

as a fraction.» step 2: Find the reciprocal of the

divisor or second fraction.» step 3: Multiply the dividend

and reciprocal of the divisor.» step 4: Write the resultant

answer in lowest terms.


Example – 1

Find 3 ÷ ¼ 3 ÷ ¼ = 3 ÷ ¼

1 Reciprocal of ¼ = 4/13 ÷ ¼ = 3 x 4 = 12 = 12.

1 1 1

Write the whole number as fraction


Example – 2

Find 4 ÷ 2/3 4 ÷ 2/3= 4/1 ÷ 2/3

= 4/1 x 3/2= 12/2 = 6.


Practice Problems

Divide:1. 3 ÷ ½ = 62. 9 ÷ 1/6 = 543. 7 ÷ 7/5 = 54. 32 ÷ ¾ = 42 2/35. 4 ÷ 1/8 = 32


Dividing a fraction by a whole number

To divide a fraction by a whole number:

Step 1: Write the whole number as a fraction.

Step 2: Find the reciprocal of the divisor.

Step 3: Multiply the dividend and the reciprocal of the divisor.

Step 4: Simplify.


Example - 1

Find ¾ ÷ 9¾ ÷ 9 = ¾ ÷ 9 1

= ¾ x 1 9

= 3 x 1 4 x 9

= 3 = 1 36 12


Practice Problems

Divide 1. 5/7 ÷ 2 = 5/142. 1/3 ÷ 13 = 1/393. 1/12 ÷ 4 = 1/484. 4/7 ÷ 5 = 4/355. 5/6 ÷ 5 = 1/66. 1/8 ÷ 4 = 1/32


Word Problems

Miss. Kate and her friend Joe made 4 pizzas. They decided that ½ pizza will be given to each person. How many of ½ pizzas were there?4 ÷ ½ = 4 x 2 = 8 pieces


Word Problem

¾ bottles of orange juice has to be poured into 6 glasses. If an equal amount of juice has to be put into each glass, how much of the juice will each glass hold?¾ ÷ 6 = ¾ x 1/6

= 1/8Each glass will hold 1/8 of the juice in

the bottle.


Now Your Turn

1. Mrs. Anne bought 50 pound bags of dog food to feed the dogs. If each dog gets 5/6 pound of food, how many dogs can she feed with one bag?

Answer: 50 ÷ 5/6 = 50 x 6/5 = 10 x 6 = 60

dogs


Another Question

2. Lucy wants to divide a sweet into five equal parts. The sweet is 5/8 feet long. How long will each sweet be?

Answer: 5/8 ÷ 5 = 5/8 x 1/5= 1/8 ft long.


Review

Any two numbers whose product is 1 are called reciprocals.

To divide a whole number by a fraction, multiply the reciprocal o the divisor with the dividend.

To divide a fraction by a whole number, multiply the reciprocal of the whole number and multiply it with the fraction.


AssessmentDivide the following:1. 1/3 ÷ 2 = 1/62. ½ ÷ 4 = 1/83. 3/5 ÷ 2 = 3/104. 2/3 ÷ 5 = 2/155. 3 ÷ 1/5 = 156. 7 ÷ 1/3 = 217. 8 ÷ 5/6 = 9 3/58. 1 ÷ 3/10 = 3 1/39. 6 ÷ ¾ = 810. 9/7 ÷ 3 = 3/7


Great Job!!

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