Math Unit 2 Review
This is only a test!
6.543
0.024
792.154
Rounding
• Identify the place you are rounding to, and place a
box around it.
• Check the digit to the right. If it is greater than or
equal to 5, then the number in the box increases by
one. If it is less than 5, then the number in the box
stays the same.
• Keep everything before the box. Everything after the
box becomes zero. If the zeroes come at the end of a
decimal, they can be dropped.
Example : Round 13.56 to the nearest
tenths place.
13.56 __1 _3_ . _6_ _0_
13.6 is the answer.
Rounding Decimals
Rounding Decimals
Rounding Decimals
Mr. Pants is making a strawberry cake to share with his class.
He went to the story to buy strawberries and calculated the
costs.
Cake recipe:
• 2.14 pounds of strawberries
• Cost per pound $0.91
• Calculation : 2.14 x $0.91 =1.9474
Find the actual cost by rounding to the nearest hundredths.
Adding and Subtracting
The Basic Steps:
• Line up the numbers by the decimal point.
• Fill in missing places with zeroes.
• Add or subtract.
Example
Mr. Dunn rides his bike 400 meters in 14.45
seconds. Later that day he rode his bike another
400 meters in 12.89 seconds
How long did it take Mr. Dunn to bike 800
meters in seconds?
Mr. Dunn rides his bike 600 meters in 32.45
seconds. Later that day he rode his bike another
600 meters in 30.76 seconds
How long did it take Mr. Dunn to bike 1,200
meters in seconds?
Damien runs 1 mile to the bus stop. He has
already ran .42 miles.
How much farther does he have to run?
Damien runs 1 mile to the bus stop. He has
already ran .27 miles.
How much farther does he have to run?
Multiply Decimals:
• You do not line up the factors by the decimal.
• Instead, place the number with more digits on
top.
• Line up the other number underneath, at the
right.
• Multiply
• Count the number of decimal places (from the
right) in each factor.
• Use the total number of decimal places in your
two factors to place the decimal in your product.
Example: 5.63 x 3.7
1 two
42 one
5.63
x 3.7
11
1 39 4 1
+ 16890
20.8 31 three
• Mr. Chicken makes 4 dollars an hour at his job.
If worked 3.5 hours how much did he make?
Try This: 6.5 x 15.3
31 one
21 one
15.3
x 6.5
1
765
+ 9180
9 9.4 5 two
Dividing Decimals
Dividing Decimals with Models
Dividing Decimals
WATCH
https://www.youtube.com/watch?v=py
Qf8uaSirw
Add and Subtract Factions
• List the multiples of both denominators.
• Find the least common multiple (LCM).
• Write new fractions with the LCM as the new
denominator.
• Find the factor you multiply by to get from your
original denominator to your new denominator.
• Use that same factor, and multiply it by your
original numerator to get a new numerator.
WHAT DOES THAT MEAN?
Let’s illustrate the steps with an
example.
3 +1
46
3+ 1
4 6
x3 9 2 x2
12 12
+
11
Multiples of 4: 4, 8, 12, 16, 20 12
Multiples of 6: 6, 12, 18, 24, 30
Example 2
9 2 10, 20, 30, 40, 50
5 5, 10, 15, 20, 25
10
4 x2 5
x1 10
= 10
9 1
10 = 2
Add and Subtract Mixed Numbers and
Improper Fractions
• Method 1
https://www.youtube.com/watch?v=LMAOcfhvrYo&feature=youtu.be
• Method 2
https://www.youtube.com/watch?v=X-ebopde6YY&feature=youtu.be