How to Be a Mathemagician

256 Pages·2017·5.09 MB·English

by  Singhal

ADITI SINGHAL
SUDHIR SINGHAL

HOW TO BE A MATHEMAGICIAN
PENGUIN BOOKS
CONTENTS
Introduction
PART A: PROBLEMS WITH SURPRISING SOLUTIONS
1. Which Pizza Do You Prefer?
2. Exponential Mystery
3. Smart Business
4. The Invisible Thief
5. Three in a Race
6. Clever Salesman
7. Solving Questions without Algebra
8. Comparing Movies
9. Matchstick Puzzles
10. Observation-Enhancing Puzzles
PART B: CALCULATIONS WITHOUT CALCULATORS
11. How Long Does It Take to Double Your Money?
12. Determining the Unit Digit at a Glance
13. Shortcut to Find the Sum
14. Magic by
15. Wonder of 9s
16. Learning the Times Tables
17. Amazing Squares
18. Simplifying Multiplication
19. Magical Division
20. Quick Cube Roots
21. Quick Calculations of Compound Interest
22. The Prime Check
23. Comparing Surds
PART C: INTERESTING MATHS FACTS
24. Races on Tracks
25. Maths behind Credit/Debit Cards Numbering
26. Why Is 1 One, Why Is 2 Two?
27. Is Zero Even or Odd?
28. Why Is Division by 0 Not Defined?
PART D: MATHEMAGICIAN TECHNIQUES FOR COMPETITIVE EXAMS AND INTERVIEWS
29. An Interview Question
30. Handshakes
31. Investigating Squares
32. Investigating Triangles
33. Crack the Code
34. Out-of-the-Box Thinking
35. Presentation of Data
36. Are You Maths Smart?
37. Calendar at Your Fingertips
38. Cool Maths
Acknowledgements
Advance Praise for the Book
‘This book will make you fall in love with several topics—exponentials, for
example. What I like most about its contents is that it not only explains the
concept concisely, but also enlists real-life applications of the same. This is
handy and provides clarity to students so that they can see where they will
actually apply this knowledge once they are out of the classroom. Give it a read.
You will be glad that you did!’
—H.S. Anand, zonal director, Akal Academies
‘Just like magicians performing tricks with a wave of their wands, Aditi and
Sudhir have turned maths into a fascinating “world of wonder” with their new
book. Becoming a maths wizard is now astonishingly easy with their interesting
tricks and amazing mathematical facts. Just go through the pages, and amaze and
impress your friends and audience with your superpowers of the mind! It’s as
easy as abracadabra!’
—Sharon Galstaun, academic head, St Karen’s High School and St Karen’s
Secondary School, Patna
‘Aditi and Sudhir Singhal’s book How to Be a Mathemagician is for those who
love maths as well as for people with maths-phobia. They have a knack of
making this subject interesting and easy. Their sincere efforts and dedication in
this field have given them a place among renowned and recognized authors of a
subject that is of great value for today’s student’
—Goldy Malhotra, director, Academic Staff Training College and
Administration, Manav Rachna International Schools
‘This book will make maths understandable to all learners. It will help students
prepare for any entrance examination where arithmetic has weightage, and
teachers and mentors will find it very useful. I congratulate Aditi and Sudhir on
making learning maths fun’
—Lalit Sharma, president and principal, FCS Foundation School, Punjab
—Lalit Sharma, president and principal, FCS Foundation School, Punjab
‘How to Be a Mathemagician is a brilliant piece of work to strengthen and
expand mathematical notions. It is a wonderful resource for teachers who want
to increase active participation of students in maths lessons. Magic tricks,
problem-solving methods and calculation techniques are specially beneficial for
the students’
—Sharmila Singh, principal, Pioneer Montessori Inter College, Eldeco-I,
Lucknow
‘How to Be a Mathemagician is a wonderfully entertaining and interesting book
for adults and children alike. It kept my children engrossed for hours. They
enjoyed learning the concepts and doing the magic tricks with their friends. It’s
written in a way that is easy to understand. The best part is that children don’t
even realize they are doing maths while having so much fun. I would highly
recommend this book for all ages’
—Sona Sood, professional photographer
‘This book is a treat for both children and adults alike. It is a collection of
engrossing tricks that will keep you on your toes all throughout. This book is
especially helpful in gaining insight into new ways of teaching some difficult
concepts to children in a more friendly manner. I extend my heartfelt
congratulations to both the authors of this book for creating a marvellous
mathematical journey for us to experience’
—Ashima Gupta, PhD, economics
To the
Almighty God,
the Supreme father of all souls and
the source of true knowledge
Why do children dread mathematics?
Because of the wrong approach.
Because it is looked at as a subject.
Shakuntala Devi
Introduction
M
athematics is not just a subject but a part of our lives. Whether you are a
child or a grown-up, a student or a professional, a musician or a magician, maths
plays an important role in your daily routine. You can even find mathematical
patterns in spiderwebs or honeycombs.
Learning maths can be made enjoyable if it is taught through activities,
puzzles and games right from an early age. Many a time, we find that some
students solve complex maths problems in minutes while some take a long time
to solve even the basic ones. Contrary to popular belief, it’s not their level of
knowledge that leads to this difference but the way they apply their knowledge.
This book is written with the aim of enhancing the power of reasoning, critical
thinking and the problem-solving ability of the reader. It is intended for students,
teachers and parents alike, as the learning of mathematics is not restricted to any
age. For students who find themselves afraid of the subject, we have attempted
to make it fun to learn and give them the confidence to approach each problem
with a fresh perspective. We have also written this book for teachers, who can
use many of the activities mentioned to make their classes livelier and show their
students that maths need not be a dreaded subject. Parents can also pick up this
book to make it easier to explain complex concepts to their children and help
them develop a strong base in the subject. It contains mind-bending questions
with unusual solutions, logic-related maths problems, interesting maths facts and
proofs, and calculation tips that highlight the almost magical simplicity of the
subject.These are effective methods that help in day-to-day application of
mathematics, while reducing one’s dependency on gadgets as well as providing
good practice for the types of questions that are asked in examinations and
interviews.
The other section of this book contains some amazing magic tricks and
enthralling activities—just flip the book to find them!
You might find some parts of the book challenging even after reading and
rereading the solutions. If so, keep going. Even without necessarily