January sale! Get 25% off of all of Math Mammoth products sold on this site. Use coupon code MMJAN18. The offer is valid till January 31, 2018.
Math Mammoth on Facebook

Math Mammoth on Google+

You are here: HomeBlue Series → Decimals 1

Math Mammoth Decimals 1

Math Mammoth Decimals 1 math book cover
69 pages
(answers included)

Sample pages (PDF)
Contents and Introduction
Adding and Subtracting
with Tenths

Rounding to the Nearest
Whole Number

Prices & ordering

PDF download $3.50

Add to cart

You will be purchasing the downloads from my authorized reseller Comecero, LLC.

Printed copy $8.95, b&w

Buy at Lulu

small flag of SpainEste libro en español

Math Mammoth Decimals 1 is an introduction to decimal numbers, and is best suited for 4th to 5th grade math.

The PDF version of this book is enabled for annotation. This means that if you prefer, the student can fill it in on the computer, using the typewriter and drawing tools in Adobe Reader version 9 or greater.

This book deals with decimal numbers that have tenths and hundredths - numbers with a maximum of two decimal digits. We only deal with some of the basic operations: addition, subtraction, and multiplication by a whole number, with a strong emphasis on mental calculations. The idea is to lay a solid conceptual foundation so that the student does not succumb to rote memorization of rules and procedures without understanding.

The two operations not studied in this book are multiplying a decimal by a decimal and decimal division. Those can be found in Math Mammoth Decimals 2.

We use number lines, fraction models, and place value charts to teach the concepts of tenths and hundredths. In studying addition and subtraction, we compare decimal operations with corresponding fraction operations in order to show why they work.

A common student error is to add 0.4 + 0.8 = 0.12. Here, the student may be considering the decimal part of a number as a 'separate whole number', and try to apply whole number arithmetic within the decimal part. To help such a student, read the decimals as fractions and emphasize how fractions are added. Think: four tenths plus eight tenths equals twelve tenths, which is 1.2.

When we add decimals of different "length" (numbers with different amounts of decimal digits), such as 0.4 + 0.08, you can "tag" a zero onto the end of 0.4 to make adding easier. The problem becomes 0.40 + 0.08. Now, both addends have hundredths, so the answer is simply 48 hundredths or 0.48. This is the same thing as converting the corresponding fractions (four tenths and eight hundredths) to have the same denominator (forty hundredths and eight hundredths).

Other topics covered are comparing decimals, multiplying a decimal by a whole number, rounding, estimating, and money problems.

Several videos from my Decimal arithmetic playlist can be used in conjunction with this book.

You might also be interested in:
From a homeschooling parent who has used Decimals 1 with a 5th grader:

My 5th grader and I worked through the decimals book. It actually helped me to understand decimals a lot better also. We were both amazed at how easy they are to work with once you understand the concepts behind them.

I love the books. They include a lot of thinking and reasoning skills that our other math program did not include. They also present things in a simple clear manner. No more tears when it comes to decimals!!!

Michele Cutlip

Better Yet - Bundle Deals!

Blue Series - $120 (download) or $125 (CD)
Blue Series for grades 1-3 - $45 (download)
Blue Series for grades 4-7 - $75 (download)

Light Blue Series, grades 1-7 - $175 (download) or $180 (CD)
Light Blue Series, grades 1-3 - $75 (download)
Light Blue Series, grades 4-7 - $100 (download)

Golden/Green Series - $65 (download) or $70 (CD)

All Inclusive Bundle - $233 (download) or $238 (CD)

"Everything" Bundle - $299 (download only)

Learn more about these Math Mammoth bundles!

How and where to order

You can buy Math Mammoth books at:

  • Here at MathMammoth.com website — simply use the "Add to cart" buttons you see on the product pages.
  • CurrClick.com carries all Blue, Golden, and Light Blue series books as downloads. They accept credit cards and Paypal. You will be able to download the products immediately upon the purchase, and also return to your account at CurrClick to redownload.
  • Rainbow Resource carries printed copies for the Light Blue series books, plus several CDs (Light Blue and Blue series).
  • Homeschool Buyers Co-op offers download versions of the Light Blue series, plus the Blue series bundle.
  • Educents carries download versions of the Light Blue and Blue series.
  • K5 Learning offers download versions of the Blue series.
  • Lulu offers printed copies for the Blue, Golden, and Light Blue series books.

By purchasing any of the books, permission IS granted for the teacher (or parent) to reproduce this material to be used with his/her students in a teaching situation; not for commercial resale. However, you are not permitted to share the material with another teacher.

In other words, you are permitted to make copies for the students/children you are teaching, but not for other teachers' usage.

Math Mammoth books are PDF files. You will need Adobe Reader to view them, including if you use a Mac or Linux. You can try other PDF viewers, but they seem to either omit or mess up some of the images.

Math Mammoth Tour

Confused about the different options? Take a 7-day virtual email tour around Math Mammoth! You'll receive:

An initial email to download your GIFT of over 400 free worksheets and sample pages from my books; 6 other emails on 6 subsequent days that describe the different series of Math Mammoth products, answering the most commonly asked questions, including "What is the difference between all these different-colored series?"

This way, you'll have time to digest the information over one week, plus an opportunity to ask me personally which book would be right for your child or students.

Note: You will FIRST get an email that asks you to confirm your email address. If you cannot find this confirmation email, please check your SPAM/JUNK folder.

"Mini" Math Teaching Course

This is a little "virtual" 2-week course, where you will receive emails on important topics on mathematics education. The topics include:

- Teaching multiplication tables
- Why fractions are so difficult
- How to help a student who is behind
- Should you use timed tests
- The value of mistakes
- And more!

You will also receive a GIFT of over 400 free worksheets and sample pages from my books right in the very beginning. smile

Note: You will FIRST get an email that asks you to confirm your email address. If you cannot find this confirmation email, please check your SPAM/JUNK folder.

Math teaching tips & resources

Enter your email to receive math teaching tips, resources, Math Mammoth news & sales, humor, and more! I tend to send out these tips about once monthly, near the beginning of the month, but occasionally you may hear from me twice per month (and sometimes less often).

Peek at the previous tips here.

You will also receive:

  • A GIFT of over 400 free worksheets and sample pages from my books.
  • Once or twice a year, you may also receive an email where I promote something from Inspire4.com — I simply want to spread the word about it.

© 2006-2018 MathMammoth.com