Doubling and Halving
Use the doubling and halving strategy to solve.
21 x 40=
42 x 20=
84 x 10= 840
28 x 17 = (20 + 8) x (10 +7)=
True
Make a ratio table to solve: 135 divided by 9
Answer is 15
4 friends went to the movies. They shared the cost evenly among themselves. The total cost was $44.00, how much money did each person pay?
$11.00
Find the mistake;
1000
-345
Answer should be 655, the 0 in the hundreds place should be a 9.
Jane used the halving and doubling stategy to solve
25 x 32= __ Fill in the blanks on the arrays on the board.
Missing boxes are 64, 100 and 128, 12,800
33 x 65- (30 x60) + (3 x 5)
False, 33 x 65 = 2,145 not 1,815.
Fill in the blanks on the ratio table shown.
26, 5, 10, 20
3 friends went together to buy a gift. They each paid $6.00. How much did the gift cost?
$18.00
Find the mistake:
50 x 200=
Should be 100 x 100 = 10,000
True or False?
43 x 34 = 86 x 18
False
43 x 34 = 86 x 17
41 x 16= 40 x 17
False, 41 x 16= 656 and 40 x 17= 680
Use a ratio table to solve 342 divided by 9.
38
Possible solutions on the table
1 2 3 8 20 30
9 18 27 72 180 270
There are 6 friends going to a basketball game. The total cost of the game is $168.00. How much does each person have to pay?
$28.00
If Mrs. Life buys 4 dozen cookies for our class. How many cookies will each person receive? How many extra cookies will there be? What will she do with any extra cookies?
4 x 12 = 48 cookies
48 divided by 21 = 2 cookies each with 6 extra cookies.
Max used halving and doubling to find 12 x 40=
Fill in the blanks and the equations to represent his work.
12 x 40= 24 x 20= 48 x 10= 480
43 x 16 = 16 x (40 + 3)
True
Create a ratio table to show 5 x 35 =
175
1 2 5 10 20
5 10 25 50 100
5 friends are going to a concert. They are paying a group rate of $225.00. How much does each person have to pay?
$45.00
Write down two equivalent fractions for 1/2.
2/4, 3/6, 4/8, etc.
Shin used a doubling and halving strategy to solve
25 x 84. Fill in the blanks to represent her work.
42, 100, 21
25 x 84= 50 x42= 100 x 21= 2100
34 x 20 = 68 x 40
False
Create a ration table to solve 289 divided by 7=
41 R 2 Possible Solution:
1 2 4 40
7 14 28 280
Our class of 21 students is buying balloons for a party. Balloons cost $9.00 per dozen. If each person brings in $3.00, how many balloons will they buy?
7 dozen or 84 balloons.
Complete the line plot for the data on Hand Spans.
What is the range of hand spans?
Completed line plot with all 6 x's and 2 inches.