Homeschool Math, www.HomeschoolMath.net website logo

Blog | Newsletter | EBooks | Worksheets | Curriculum Guide | Reviews | Lessons & Articles | Amazon Store |
NEW!
Grade 5 worksheets - ready-made worksheets, yet different (randomly generated) each time.

Featured!
Thanksgiving contest - win some of my books!

Latest from my blog
This is where you'll find the latest happenings, news, & ideas in math teaching

Newsletter
Subscribe or see the past volumes. Filled with math teaching information.
starNovember 2008 newsletter

Hover your mouse above to open a menu of various worksheets you can generate for free!

Advice, reviews, and resources to help you choose a math curriculum!

Games you can play online, interactive tutorials, fun math websites and more. Arranged by topic/level for ease of use.

Learn how to TEACH concepts or about general concerns in math education.

Reviews
In-depth reviews of math products

Math help & tutoring
A list of free message boards, math help websites, and online tutoring services. Click here for an online tutor!

My Amazon Store
See some math products I recommend.

I have two games on my site, plus links to many.

 
Math Mammoth Decimals 1 book cover The ideas in this decimals lesson are taken from
Math Mammoth Decimals 1 book ($4.00 download). Only a few examples of each problem type are shown.

Multiplying hundredths
Free decimals lesson plan from HomeschoolMath.net

Multiplication by a whole number is repeated addition!  Try these problems.  Don't get fooled!

4 × 0.05 = 0.05 + 0.05 + 0.05 + 0.05 = ___

5 × 0.09 = 0.09 + 0.09 +

2 × 0.12 = 

2 × 0.81 = 

Remember, when you add hundredths, your answer also will have hundredth parts. And multiplying by a whole number is essentially adding.  Compare:

3 × 40 = 40 + 40 + 40 = ____

3 × 4 = 4 + 4 + 4 = ___

3 × 0.4 = 0.4 + 0.4 + 0.4 = ___

3 × 0.04 = 0.04 + 0.04 + 0.04 = ___

6 × 70 =

6 × 7 =

6 × 0.7 =

6 × 0.07 =

 

Example problem types

1.  Multiply by a whole number and compare the problems.  Think of addition - and you get help from multiplication tables too.

a. 5 × 100 = ____

5 × 10 = ____

5 × 1 =  ___

5 × 0.1 = ___

5 × 0.01 = ___

d. 9 × 800 = ____

9 × 80 = ____

9 × 8 = ___

9 × 0.8 = ___

9 × 0.08 = ___

e. 7 × 700 = ____

7 × 70 = ____

7 × 7 =  ___

7 × 0.7 = ___

7 × 0.07 = ___

h. 3 × 3100 = ____

3 × 310 = ____

3 × 31 = ___

3 × 3.1 = ___

3 × 0.31 = ___



2.  Continue the patterns!  Use adding to multiply by a whole number, or your multiplication tables.

a.

9 × 0.01 = 

9 × 0.02 = 

9 × 0.03 =  

9 × 0.04 = 

 

 

 

 

 

d.

5 × 0.00 =

10 × 0.01 =

15 × 0.02 =

20 × 0.03 =

 

 

 

 

3.  Explain why 6 �0.3 is NOT 0.18.  Then find two numbers (not 1) whose product is 0.18.

 

4. Imagine nine little lines between each of the decimals on the number line below.

 

Which numbers do they represent?

Which of those are closer to 0 than to 1?         Which are closer to 1?

 

5.  Round the following decimals to the nearest whole number.   Remember 0.50 is same as 0.5, so is rounded up to 1.

a. 0.18 ≈ b.  0.51 ≈ f.  4.35 ≈
m.  7.7 ≈ n.  8.32 ≈ r.  4.3 ≈


6.  Estimate the result of the multiplication problem by rounding the decimal number to the nearest whole number.

a.  2 × 3.24 ≈ 6
(since 3.24 ≈ 3) 
d.  13 × 2.24 ≈

 

But when estimating, don't round anything to zero!  Look how silly estimations you would get:

0.32 ≈ 0, so  7 × 0.32 ≈ 0 !!!  This does not make any sense.

Instead, round 0.32 to 0.30, and get 7 × 0.30 ≈ 2.10

 

e.  6 × 0.24 ≈ 
 
h.  3 × 1.05 ≈
i.  9 × 4.52 ≈ 
 
l.  13 × 1.21 ≈


7.  Find the missing factor.

a.  2 × ___ = 0.08 d.  __ × 0.09 = 0.63
e.  3 × ___ = 0.36 h.  4 × ___ = 0.84
i.  __ × 0.11 = 0.77 l.  12 × ___ = 0.6

 

4 × 2.14

Estimation: 2.14 is between 2 and 3 but closer to 2.  So 4 × 2.14 will be between 4 × 2 and 4 × 3, or between 8 and 12, but closer to 8.

Think.  4 × 2.14 is the same as

2.14 + 2.14 + 2.14 + 2.14

1   
214
×   4

856

If  4 × 214 is 856, how could you
use that to find the answer to 4 × 2.14?


 
5 × 3.13   = 3.13 + 3.13 + 3.13 + 3.13 + 3.13  =  15.65
whole 
number
times a decimal with
hundredths
is the same as adding
decimals with hundredths,
so the answer will have
hundredths too!

  
When multiplying in columns, just put the decimal point in the right place. Compare:

3 × 2.27

Estimation: 2.27 is close to 2.  
So 3 �nbsp;2.27 is about 3 �2 = 6.

Calculation:

 2   
2.27
2.27
+   2.27

 6.81

 2   
2.27
×   3

6.81

 
When you add,
the answer 
has hundredths.
 
...
 
So when you multiply,
the answer must have
hundredths too.

 

When estimating, one method is to round the number to the biggest place value it has.  For example, 56 would be rounded to nearest ten, and 228 to the nearest hundred.

In case of decimals, you can often simply round to the nearest whole number.  For example, 3.87 would be rounded to 4.  15.26 would be rounded to 15.

8.  Multiply in columns.  Estimate first!

a.  4 × 6.37 d.  6 × 15.85
Estimation: Estimation:

 

 


 



i.  22 × 8.06 l.  9 × 4.95
Estimation: Estimation:

 

 

 

 

 

Money

In the USA, money comes in dollars and cents.  The word cent comes from from the Latin word cent"simus which means hundredth.  Cents are hundredth parts of a dollar.  That is why 1 dollar has 100 cents.  In many countries of the world, the main money unit is also divided into 100 parts.

Usually money amounts are given in dollars, using the decimal digits to tell how many hundredths, or how many cents.  For example:

$14.59 means 14 whole dollars, and 59 cents (59 hundredth parts)

You can now apply your knowledge of how to add and multiply decimals to various money problems.

 
9.  Times 25 cents.  Note the pattern. 

1 × $0.25 =
2 × $0.25 =
3 × $0.25 =
4 × $0.25 =
5 × $0.25 =
6 × $0.25 =
7 × $0.25 =
8 × $0.25 =
9 × $0.25 =
10 × $0.25 =
11 × $0.25 =
12 × $0.25 =
13 × $0.25 =
14 × $0.25 =
15 × $0.25 =
16 × $0.25 =


Mental math ideas 

1)  7 × $8.99.  Since $8.99 is just one cent less than $9, first calculate 7 × $9, and subtract from that 7 × 1 cent.  Result $ _____

2)  6 × $4.05.  Just multiply separately the dollars and cents: 6 × $4 is $24, and 6 × 5 cents is 30 cents.  Total $ _____

3)  4 × $3.25.   Multiply dollars and cents separately. Remember 4 × 25 cents is 1 whole dollar. Total $ _____

4)  5 × $6.25.   Multiply dollars and cents separately.  Since 4 × 25 cents is 1 dollar, then 5 × 25 cents make $1.25. Total $ _____

5)  2 × $1.75.  Two times 75 cents is $1.50.  Total $ _____

6)  4 × $3.75.  Calculate 4 × $4, and subtract from that 4 × 25 cents.  Total $ _____

7)  $100 - $34.57.  Subtract each of the digits 3, 4, and 5 from 9.  The last one, 7, subtract from 10.  To see the reason for this rule, subtract in columns and do all the borrowings.  

8) $10 - $5.38.  Subtract the digits 5 and 3 from 9.  The last one, 8, subtract from 10.  Result $_____

9) Subtraction itself may be easier by thinking of the difference  or "adding up to".  For example $10 - $3.76.  Difference of 3 and 9 - six.  Difference of 7 and 9 - two.  Difference of 6 and 10 - four.  Result $_____

10)  $1 - $0.73.  Subtract or find the difference of 7 and 9.  The last one, 3, subtract from 10.  Result $ _____

 
10.  Find the change for items with these prices.   Use the mental math rule "Subtract all digits from 9 except the last one from 10."

from $10:

a.  $4.76

b.  $2.38

c.  $9.23

from $100:

m.  $24.35

n.  $81.95

o.  $45.54

 

11.  Word problems. 

a.  A pencil costs $0.45,  an eraser $0.30, and a pencil sharpener $0.30.  What is the cost of all three?

You give $5 for the purchase.  What is your change?
  

c.  Lucy bought two pairs of jeans for $15.99 each, and two sweaters for $8.75 each.  What was her total bill?  Estimate the bill first.


 

d.  Jean has $20, and he wants to buy seven pairs of socks for $2.95 each.  First estimate his bill.  Then calculate the exact bill.  Will he have enough money?  

If yes, calculate the change.  If no, calculate how much more he would need.

 

h.  Take a grocery store receipt, and imagine you're going through the store picking the items.  Estimate the cost of each item and add them up as you go.  How close does your estimation come to the actual cost? ( It is very good to practice this with several receipts, in fact.)

Example:

tomatoes $0.45
cucumber $0.19
butter $2.35
eggs $2.57
honey $3.89
celery $1.03
--------------
total $10.48
estimation
tomatoes $0.50
cucumber $0.20 (sum 0.70)
butter $2 (sum 2.70)
eggs $2.50 (sum 5.20)
honey $4 (sum 9.20)
celery $1 (sum 10.20)
---------------------------
estimated total $10.20

 

Next lesson: Comparing decimal numbers


Math Mammoth Decimals 1 book cover The ideas in this decimals lesson are taken from
Math Mammoth Decimals 1 book ($4.00 download). Only a few examples of each problem type are shown.






- Learn subtraction concept
- fact families
- memorize basic facts
- word problems
- colorful pages.
- download & print.
Self-teaching worktext.

Download today!






 




Subscribe for free
HOMESCHOOL MATH NEWSLETTER

When you subscribe, you will also receive a GIFT of over 280 FREE math worksheets and sample pages from Math Mammoth books for grades 1-8!

Homeschool Math Newsletter comes out once monthly, and is filled with math teaching articles and tips, Math Mammoth news, and all kinds of little "tidbits" such as math news, interesting links, or humor. The content is equally good for all of us who teach math (not just homeschooling parents).

Take a peek at the previous volumes here!.

Note: This is a double opt-in list. You will FIRST get an email that asks you to confirm your email address. PLEASE check also your SPAM/JUNK folder for this confirmation email.

The newsletter service is by Aweber.com. Your email address will not be shared, sold, or distributed to anyone else.


Download 280+ QUALITY math worksheets without cost
Link to us    Sitemap    Contact    About    Privacy    Advertise    Homeschool links    Educational links
Best Homeschool Sites on the Internet - Homeschool Top Sites
Copyright 2003-2008 Homeschool math
http://www.homeschoolmath.net/


 

 

P.S. ....

 

Check out these short video clips from my favorite band - 24K Gold Music Shows. They play oldies, Elvis, country, and top hits of the 50s and 60s. It's a show with large band, costumes, choreography, little skits, dancing/singing girls, junior dancer troupe, etc.

"Please Mr. Postman"
originally by the Marvelettes

Impossible Dream (Elvis song)
Most importantly, the band wants to use the uplifting and energetic music to bring some fun, happiness and encouragement into people's lives. They're doing it selflessly to help others, and don't get paid for any of it themselves. And I admire that!

=> See more video clips at YouTube