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The cover page of the book, featuring a boy, a girl, two number characters, and a giant number 1.  The book title reads Happy Math 1: Numbers, written by Mala Kumar, Illustrated by Angie & Upesh.

Happy Math 1: Numbers, by Mala Kumar

©Pratham Books, 2007 First Edition 2007Illustrations: Angie&Upesh ISBN 978-81-8263-906-5Registered Office: PRATHAM BOOKSNo.633/634, 4th “C” Main, 6th ‘B’ Cross, OMBR Layout, Banaswadi,Bangalore- 560043.&080 - 25429726 / 27 / 28 Regional Offices:Mumbai&022 - 65162526 New Delhi&011 - 65684113 Typsetting and Layout by: The Other Design StudioPublished by: Pratham Books (External Link)

A girl and a boy read a book together.

Sankhya and Ganith have been learning a lot of things in their mathematics class.Join Sankhya and Ganith in their happy discoveries about mathematics.Zzero and Eka are friends of Sankhya and Ganith. In this book Sankhya and Ganith discover the magic of numbers. They think of numbers as their friends.They want to share some of the things they have found out about numbers.They learnt about numbers from stories that they read in many books in their school library.

Two number characters wave at the reader.

The big challenge

A cartoon number one watches as a number zero bounces around.

Eka: Zzero ! Will you stop bouncing around like this, please?
Zzero: I’m happy. So I’m bouncing. I can take on so many shapes.

A cartoon number one looks down on a sad-looking number zero.

Eka: Stop boasting. Do you know how many numbers you can make up? 0, 10s, 100s, 1,000s and 10,000s. That’s a lot of numbers.0, 10, 20, 30, ….90, 100, 101, 110, 200, 201, 210, ….

A cartoon number one looks down on a sad-looking number zero.

Zzero: Please stop! I want to find out how many numbers exist between 0 and 10,000 with one or more zeroes in them. The firstone is 0 and the last is 10,000 so that makes two…

A cartoon number one looks down on a sad-looking number zero.

Eka: Zzero, hats off to you for saying you will take up such a BIG challenge. I think you should first try to find out how manynumbers have one or more zeroes between 0 and 1,000.

Readers, can you help us please ?

Grains of rice

Acharya Vinoba Bhave was a freedom fighter. He followed the teachings of Mahatma Gandhi and lived between the years 1895and 1982.

When he was a young boy in Maharashtra, his mother had made a vow of offering 10,000 grains of rice to God. She carefully counteda hundred grains each day and offered it in prayer, reciting God’s name each time she made an offering.

Vinoba’s elder brother had an idea. He said, “Mother, why do you do this everyday? After counting a hundred grains on oneday, measure its weight. From the next day, you just have to weigh out an equal amount and offer it to God. This will save youtime and effort.”

A cartoon of Vinoba's mother explaining why she counts grains of rice everyday as she brushes his hair.

Vinoba said, “I don’t think that would be right. When you count 100 grains of rice each day, you will repeat God’s name 100 times.But if you weigh out 100 grains, you would say God’s name only once!”

Vinoba’s mother wanted tooffer 10,000 grains of rice. If each grain weighs half agram, how many grams will 100 grains weigh?
A picture of a measuring balance with 100 grains of rice on the left scale and an unknown weight on the right scale.

50 grams. If one grain weighs half-a-gram, 2 grains will weigh 1gm. How many 2’s in 100? 100 2 50 . 50 1 50 .

If Vinoba’s mother had counted hundredgrains on Day 1, and then followed her elder son’s advice,how many times would she have said God’s name till she made the complete offering?

199 times. On Day 1, she would have uttered God’s name 100 times while offering hundred grains. That would leave 9900grains (10 thousand minus 100 = 9900). 9900 divided by 100 99 . 100 99 199 .

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Source:  OpenStax, Class. OpenStax CNX. Dec 24, 2010 Download for free at http://cnx.org/content/col11261/1.3
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