Exercise 1.4 focuses on understanding the connections between different number sequences. Students learn that triangular numbers can be formed by adding consecutive counting numbers, while certain combinations of sequences can result in square numbers. By examining these relationships, students develop a clearer understanding of how mathematical patterns are interconnected and how one sequence can be generated from another.
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Download step-by-step NCERT Solutions Class 6 Maths Chapter 1 Patterns in Mathematics Exercise 1.4 and boost your understanding of patterns in visual and geometric forms. Access the free PDF now and practice with accurate answers and explanations.
1. Can you find a similar pictorial explanation for why adding counting numbers up and down, i.e., ,..., gives square numbers? Sol. When you add counting numbers up and down, like etc., you are essentially forming symmetrical shapes that resemble squares. For example:
1 = 1 (1 square dot) (forms a square) (forms a square) Each time, the numbers symmetrically increase and then decrease, giving a perfect square pattern.
2. By imagining a large version of your picture, or drawing it partially, as needed, can you see what will be the value of ? Sol. 1=1
3. Which sequence do you get when you start to add the All 1's sequence up? What sequence do you get when you add the All 1's sequence up and down? Sol. When we add all 1's sequence up we get the counting numbers, as , , , , When we add all 1's sequence up and down, we get counting numbers depend upon number of times 1 occurs.
4. Which sequence do you get when you start to add the Counting numbers up? Can you give a smaller pictorial explanation? Sol. If you add the counting numbers ( ), you get triangular numbers: This forms the triangular number sequence. Pictorial representation:
5. What happens when you add up pairs of consecutive triangular numbers? That is, take ? Which sequence do you get? Why? Can you explain it with a picture? Sol.
6. What happens when you start to add up powers of 2 starting with 1 , i.e., take , ? Now add 1 to each of these numbers -what numbers do you get? Why does this happen? Sol. When we start to add powers of 2: 1 When we add 1 to each of these numbers: We get a number sequence of powers of 2 again:
7. What happens when you multiply the triangular numbers by 6 and add 1 ? Which sequence do you get? Can you explain it with a picture? Sol. Multiplying the triangular numbers by 6 and adding 1 gives: This forms the hexagonal number sequence: Pictorial representation:
8. What happens when you start to add up hexagonal numbers, i.e., take , ? Which sequence do you get? Can you explain it using a picture of a cube?
We get the cube of consecutive numbers. i.e., ,
9. Find your patterns or relations in and among the sequences in Table 1. Can you explain why they happen with a picture or otherwise? Sol. . (consecutive multiples of 3 ). ........ (first number is 10 . Then increase of 5 in each term)
(Session 2026 - 27)