1. Multiplying whole numbers and fractions
Chapter 7 lesson 1
Multiplying whole numbers and fractions
cjm12/28/2012

2. 4/5 of 20 is the same as 4/5 x 20 or 20 x 4/5
How many are in each group?
Using 20 counters, divide them into 5 groups.
Circle 4 groups (4/5) 4
How many counters are circled? 16
4/5 x 20=16

3. Example (pg 292) 2/3 of 12 or 2/3 x 12
Using 12 counters, divide them into 3 groups. (Hint: the denominator tells you how many groups; the numerator tells you how many to circle.)
Circle 2 groups.
How many counters are circled? 8
2/3 x 20= 8

4. Try this! Draw an array for the problem on page 292.
X X X X
¾ x 16=
X X X X
How many counters did you circle?
X X X X
How many groups should you draw?
X X X X 4 12
How many groups should you circle?
So, 12 of Susan’s stamps are from the United States and 4 stamps are not. 3

5. 8 rows 2 7 14 14 Share & Show 7/8 x 16= How many rows of counters?
How many are in each row? 7
Circle ____ rows to solve.
How many counters are circle? 14

6. Use a model to solve.
2/3 x 18=
2/5 x 15=
2/3 x 6=

7. Other methods to solve these problems:15
5. 5/8 x 24= 5 8
Multiplication:
X 24 =
5 x 24= 120 8
The 8 slides over. 15
120 is an improper fraction:
divide to simplify.
8) 120
-120
15 x 8 = 120
Important!! Multiply the numerator by the
whole number.

8. Other methods to solve these problems:
24÷8=3
Division, then multiplication: 3 5 8 15
x 24=
8 ÷8=1 1
Both numbers
(24 & 8) can be
divided by 8.
(Reduce by 8)
1. Look at the denominator and the whole number. Is there a number that will go into both of them?
2. Now with 1 on the bottom, it is just 5 x 3= 15.