A Book About Number Facts
Marcia S. Freeman
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Library of Congress Cataloging-in-Publication Data Freeman, Marcia S. (Marcia Sheehan), 1937What makes ten? : number facts / Marcia S. Freeman. p. cm. -- (Math focal points) Includes index. ISBN 978-1-60044-642-9 (Hardcover) ISBN 978-1-60044-686-3 (Softcover) 1. Counting--Juvenile literature. 2. Ten (The number)--Juvenile literature. I. Title. QA113.F749 2008 513.2'11--dc22 2007018021 Printed in the USA CG/CG
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Table of Contents Ten Is a Special Number What Makes Ten? Finding Facts of Ten Glossary Index
4 10 18 23 24
Ten Is a Special Number A long time ago, people found their fingers were useful in counting. Count your fingers. Do you see why ten is an important number?
4
5
We use ten different symbols to write numbers. The symbols are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. But there is no separate symbol for ten.
6
ten’s
1
one’s
0 10 or
We write the number ten with a one in the ten’s place and a zero in the one’s place. Like this...10.
7
Ten is important in our money system, too. Ten pennies make a dime. Ten dimes make a dollar.
1¢
1¢
1¢
1¢
1¢
1¢
1¢
1¢
1¢
1¢
=
10¢ 8
10¢
10¢
10¢
10¢
10¢
10¢
10¢
10¢
10¢
10¢
=$ 1.00 9
What Makes Ten? Count your fingers. How many ways can you make ten? You can add one and nine to make ten. We write: 1 + 9 = 10.
10
1 +9 10
11
2 +8 10
Two and eight makes ten. 2 + 8 =10 12
3 +7 10
What do you need to add to three to make ten? 3 + 7 = 10 13
4 +6 10
Four and six is another pair that adds up to ten. 4 + 6 = 10 14
5 +5 10
Five plus five is easy. You can probably count by fives. 5, 10, 15, 20, 25, 30.... 15
The last pair to make ten is ten and zero. 10 + 0 = 10
16
10 +0 10
17
Finding Facts of Ten One way to start adding columns of numbers is to spot the pairs of numbers that add up to ten. Here is how it’s done:
Problem:
35 16 + 24
Step 1:
18
35 16 +24
5 10
Step 2:
35 16 + 24
5 10
15
t
he 5
Step 4:
1 35 16 + 24 75 19
5 10
15
’s pla ce
Step 3:
35 16 +24
e ac pl
oes in the ten g ’s e1 th
ne o goes in the
Let's try another problem.
Problem:
42 28 17 + 3
Step 2:
Step 1:
42 28 17 + 3
20
42 28 17 + 3
10 10
20
10 10
42 28 17 + 3 the 0
Step 4:
2 42 28 17 + 3 90 21
10 10
e lac sp
Step 3:
goes in the t en ’
20 pla ce
2 the
s e’ n goes in the o
0 0 1
To be a good mathematician, you need to know all the addition facts. Start with the numbers that make ten, and then tackle the harder ones like 12 + 3.
22
Glossary column (COL um) — a formation of numbers lined up vertically mathematician (MATH uh muh TISH un) — a person skilled in math symbol (SIM bul) — characters used to represent an amount system (SIS tum) — a group of interacting things zero (ZIHR oh) — none
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Index add 10, 13, 14, 18 columns 18 count 4, 10, 15 number 4, 6, 7, 18, 22
pairs 14, 16, 18 problem 18, 20 symbols 6
Further Reading Linde, Barbara. Math in Our School System. Rosen, 2007. Weiss, Ellen. Math in the Backyard. Children’s Press, 2007.
Recommended Websites www.learningplanet.com www.kidsnumber.com www.kidsites.com
About the Author Marcia S. Freeman loves writing. Her fifty or more children’s books include science, geography, and math. A Cornell University graduate, she has taught science and writing to children and their teachers.
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