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Chapter 1: Patterns in Mathematics

If you watch sunflowers, brick walls, rangoli designs, or the way a chessboard is laid out, you will notice something curious , order keeps showing up. Mathematics is, in large part, the hunt for that order. Every time we spot a rule that tells us "this comes next, and then this, and then this", we are doing mathematics.

In this chapter you will meet some of the most famous sequences of numbers , like the counting numbers, the even and odd numbers, triangular numbers, and square numbers , and discover that they hide surprising connections with each other. You will also see how lines, triangles, and squares can grow step by step, and how a sequence of shapes can mirror a sequence of numbers. By the end you will have started thinking like a pattern-hunter.

The reason patterns matter is that they let us predict. Once you see the rule behind the first few terms, you can leap ahead to the hundredth or even the millionth term without writing all the numbers in between. That is the power that helped humans launch rockets, design bridges, and decode DNA.

What's inside

  1. What is mathematics? , the search for patterns and explanations.
  2. Number sequences , the most famous lists of numbers.
  3. Visualising number sequences , turning lists into pictures.
  4. Patterns in shapes , sequences of dots, triangles, and squares.
  5. Linking numbers and shapes , how the two sequences talk to each other.

Key results / Formula card

SequenceFirst few termsRule
Counting numbers1,2,3,4,5,1, 2, 3, 4, 5, \dotsadd 11 each time
Even numbers2,4,6,8,2, 4, 6, 8, \dotsadd 22 each time
Odd numbers1,3,5,7,1, 3, 5, 7, \dotsadd 22 each time
Triangular numbers1,3,6,10,15,1, 3, 6, 10, 15, \dotsTn=n(n+1)2T_n = \frac{n(n+1)}{2}
Square numbers1,4,9,16,25,1, 4, 9, 16, 25, \dotsSn=n2S_n = n^2
Powers of 21,2,4,8,16,1, 2, 4, 8, 16, \dotsdouble each time

A beautiful fact you will discover: the sum of the first nn odd numbers is always a square. For example, 1+3+5+7=16=421 + 3 + 5 + 7 = 16 = 4^2.

How to read this chapter

Go through the subtopics in order. Always try to draw a picture or arrange pebbles before reading the explanation , pattern-hunting is a hands-on sport. Keep a small notebook to collect every new sequence you spot, in or out of school.

Sub-topics

5 pages

Practice quiz

Answer the questions; explanations appear after each.

Quiz
Chapter 1 : Mixed practice
10 questions · pick the best answer
Q1

Next term of 1, 4, 9, 16, ...?

Q2

1 + 3 + 5 + 7 + 9 equals:

Q3

Triangular numbers: 1, 3, 6, 10, ... next?

Q4

Number of dots in a 4×44 \times 4 square arrangement:

Q5

Cube numbers begin 1, 8, 27, 64, ... : next?

Q6

Next in Fibonacci 1, 1, 2, 3, 5, 8, ...?

Q7

Sum of first nn counting numbers (1+2+...+n) for n=10n = 10:

Q8

How many dots in a triangular arrangement with 6 rows?

Q9

Pattern 2, 6, 12, 20, ... next?

Q10

Mathematics is often called the study of: