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CAT 2025 » CAT Study Material » Data Interpretation and Logical Reasoning » Overview on Arithmetic Sequences
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Overview on Arithmetic Sequences

In this lecture we are going to learn about Overview on Arithmetic Sequences, Triangular Numbers, Square Numbers, Fibonacci Numbers and many more things.

Table of Content
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A sequence in which the difference between any two consecutive terms is constant is an arithmetic sequence. The common difference is the constant between two consecutive phrases. The common difference is the number that, when added to any term of an arithmetic sequence, gives the next term.

Arithmetic Sequences

A list of numbers is known as a sequence in mathematics. Sequences are frequently defined by a rule that specifies which numbers will appear in a list. A straightforward example of such a rule is an arithmetic progression, in which the next number in a list is obtained by adding a constant value to the previous number. The outcome is referred to as an arithmetic sequence.

Sequences of arithmetic can be used to express quantities that increase at a constant rate. For instance, if an automobile maintains a constant speed of 50 kilometres per hour, the total distance travelled will increase by 50 kilometres per hour. Numerous instances can be found in the area of finance, where rent, mortgages, bills, and other expenses are frequently paid on a recurring basis. Again, the total sum paid over a period of months or years can be represented as an arithmetic progression.

Sequences and series, which are the sums of sequences, exist in a wide variety of advanced mathematical disciplines. The study of arithmetic sequences serves as an excellent introduction to this broader subject.

As with all sequences, arithmetic sequences can be categorised as either finite or infinite.

The list of integers in an arithmetic series is finite if it finally comes to an end.

The list of integers in an arithmetic sequence is infinite if it continues indefinitely.

Arithmetic Sequence Formulas:

nth Term Formula : an= a1 + (n – 1)d

Sum of First n Terms ; Sn = n/2 (first term + last term)

Where,

an= nth term 

a1 = 1st term 

n = Number of terms

d = Common difference

Sn = Sum of n terms

Example :What is the 25th term in the sequence 21, 15, 9, 3,….?

Solution:

Given the mathematical sequence:

21, 15, 9, 3,…

Here, a1 = 21

d = a2 – a1 = 15 – 21 = -6

tenth year

a = a1 + (n – 1)d

The twenty-fifth term in the given sequence is:

a25 = a1 + (25 – 1)d

= 21 + 24 (-6)

= 21 – 144

= -123

Triangular Numbers

 As depicted in this graphic, triangular numbers are a pattern of numbers that create equilateral triangles. With each successive number in the series, a new row of dots is added to the triangle. It is essential to observe that in this instance, n equals the sequence term. Therefore, n = 1 represents the first term, n = 5 represents the fifth phrase, and n = 256 represents the 256th term.

Beginning with the zeroth triangular number, the sequence of triangular numbers is as follows:

0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666…

Sum of Triangular Numbers

In the pattern of triangular numbers you will observe, the subsequent number in the sequence has an additional row added. Let us explain in detail.

The first digit is 1

In the number 2, two dots are added to the initial number to create a row.

In the number 3, three dots are added to the second number to form a row.

Again, in the fourth number, a row of four dots is added to the third number, and so on.

Therefore, this sequence conforms to the pattern:1, 1 + 2, 1 + 2 + 3, 1 + 2 + 3 + 4,  and so on.

Square Number

A square number, also called a perfect square, is a figurate number of the form  Sn= n2, where n  is an integer. For n = 0, 1,…, the square numbers are 0, 1, 4, 9, 16, 25, 36, 49,…

For example, 4 multiplied by 4 is equal to 4-squared or 4 x 4 = 42 The exponential form of multiplying a number or integer by itself is referred to as a square number. Also, if we again multiply the number by itself, then we get a cube of the integer., a x a x a = a3.

Square numbers are always positive. If a negative sign is multiplied by itself, it results in positive sign (+). For example, (-4)2 = 16 Therefore, 16 is a positive square number whose square root is again an integer, i.e., root of16 is 4.

Characteristics of Square Numbers

  • A Square number can only finish in 0, 1, 4, 5, 6, or 9 digits.

  • Zeros at the conclusion of a perfect square are always even in number.

  • The square of even numbers is invariably even.

  • Always, the square of odd numbers is odd.

  • If a number has 1 or 9 in the unit place, it is a prime number.

  • Its square culminates in 1

  • If a number has the digits 4 or 6 in the unit place. 

Fibonacci Numbers

Fibonacci numbers are a sequence of whole numbers arranged as 0, 1, 1, 2, 3, 5, 8, 13, 21, 34,… Every number is the sum of the preceding two numbers .

Here are some intriguing Fibonacci number facts:

  • This sequence is known as the Fibonacci sequence, and it is endless.

  • Each number in the Fibonacci sequence or series is denoted by the symbol Fn.

Conclusion

In real life, the arithmetic sequence is vital because it enables us to comprehend things through the usage of patterns.

The significance of the Fibonacci sequence is due to the so-called golden ratio of 1.618 or its inverse, 0.618.

Knowing your square numbers will aid you in solving a variety of different math problems, including long multiplication, area, completing investigations, and locating the square root.

As triangular numbers form a pattern, they are a good tool for teaching children in Key Stage 2 and upwards to consider algebraic functions and the significance of number formulas. 

faq

Frequently asked questions

Get answers to the most common queries related to the CAT Examination Preparation.

Why are square and triangle numbers significant?

Triangular and square numbers are common in both the natural and artificial worlds. They are quite valuable. Triangu...Read full

What is the standard rule for generating triangular numbers?

Triangular numbers are a sequence of numbers that create triangles with equal sides. T = (n)(n + 1) / 2 is the formu...Read full

What is the practical application of squares?

Finance, normal distributions, lengths and distances, the quadratic formula, the radius of circles, simple harmonic ...Read full

Why is the square root of 2 significant?

In twelve-tone equal temperament music, the frequency ratio of a tritone interval is the square root of two. The rel...Read full

What are the Fibonacci sequence's square numbers?

0 ,1 and 144 are the only square Fibonacci numbers.

Triangular and square numbers are common in both the natural and artificial worlds. They are quite valuable. Triangular numbers are frequently encountered in probabilistic circumstances, especially when determining the number of possible item pairings. The simplest example of a quadratic function is square numbers.

Triangular numbers are a sequence of numbers that create triangles with equal sides. T = (n)(n + 1) / 2 is the formula for determining the nth triangular number.

Finance, normal distributions, lengths and distances, the quadratic formula, the radius of circles, simple harmonic motion, and standard deviation all utilise square roots.

In twelve-tone equal temperament music, the frequency ratio of a tritone interval is the square root of two. The relationship between f-stops in photography lenses is determined by the square root of two, which means that the ratio of the areas of two subsequent apertures is 2.

0 ,1 and 144 are the only square Fibonacci numbers.

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