The CAT QA section requires speed and accuracy, along with a thorough understanding of the Number System. This article provides a set of MCQs on Number System to help you understand the topic and improve your problem-solving skills with the help of detailed solutions by ensuring conceptual clarity, which will help you in the CAT preparation.

Whether you're revising the basics or testing your knowledge, these MCQs will serve as a valuable practice resource.

The CAT 2025 exam is expected to follow a similar trend to the CAT 2024, with 22 questions from the QA section out of a total of 68 questions.

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CAT MCQs on Number System

CAT MCQs on Number System

1. Consider a sequence \( S \) whose \( n \)th term \( T_n \) is defined as \( T_n = 1 + \frac{3}{n} \), where \( n = 1, 2, \ldots \). Find the product of all the consecutive terms of \( S \) starting from the 4th term to the 60th term.
A
1980.55
B
1985.55
C
1990.55
D
1975.55

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2. Let \( P = \{2, 3, 4, \ldots, 100\} \) and \( Q = \{101, 102, 103, \ldots, 200\} \). How many elements of \( Q \) are there such that they do not have any element of \( P \) as a factor?
A
20
B
24
C
21
D
23

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3. Find the remainder when \( 2^{1040} \) is divided by 131.
A
1
B
3
C
5
D
7

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4. \( p \) is a prime and \( m \) is a positive integer. How many solutions exist for the equation \[p^5 - p = (m^2 + m + 6)(p - 1)?\]
A
0
B
1
C
2
D
Infinite

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5. A certain number written in a certain base is 144. Which of the following is always true?
A
I. Square root of the number written in the same base is 12
B
II. If base is increased by 2, the number becomes 100
C
Neither I nor II
D
Both I and II

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6. When asked for his taxi number, the driver replied, “If you divide the number of my taxi by 2, 3, 4, 5, 6 each time you will find a remainder of one. But if you divide it by 11, the remainder is zero.” What is the taxi number?
A
121
B
1001
C
1881
D
781

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7. Sujith says: - Multiplying first two digits by 3 gives all ones.
- Multiplying next two digits by 6 gives all twos.
- Multiplying last two digits by 9 gives all threes.
What is the sum of digits in the number?
A
30
B
33
C
60
D
45

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8.

Three words “Madhu”, “Sweet”, and “House” blink as follows: 
- Each word flashes at regular interval and stays ON for 1 second. 
- "Madhu" every 3.5 s, "Sweet" every 5.25 s, "House" every 6.75 s.
All three flash together at 8:00 a.m. Find time until next flash where last two words ("Sweet" and "House") flash together.

A
45 seconds
B
22.5 seconds
C
112 seconds
D
6.75 seconds

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9. What is the number of positive integers less than or equal to 1000 that are divisible by neither 2 nor 5?
A
400
B
300
C
500
D
600

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10. The ratio of two numbers is 3:4. If their sum is 70, what is the larger number?
A
30
B
40
C
50
D
60

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11. What is the sum of the first 20 terms of the arithmetic sequence 3, 7, 11, …?
A
800
B
820
C
840
D
860

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12. If \( \sin \theta + \cos \theta = \sqrt{2} \), what is \( \sin \theta \cos \theta \)?
A
\( \frac{1}{2} \)
B
\( \frac{1}{4} \)
C
\( \frac{1}{3} \)
D
\( \frac{1}{6} \)

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13. A number when divided by 7 leaves a remainder of 4. What is the remainder when the square of the number is divided by 7?
A
1
B
2
C
3
D
4

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14. If \( r, s, t \) are consecutive odd integers with r
A
\( r + t = 2s \)
B
\( r + t = 2s + 2 \)
C
\( r + s = t - 2 \)
D
\( r + t = 2s + 5 \)

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15. \( P, Q, R \) are three consecutive odd numbers in ascending order. If the value of three times \( P \) is three less than two times \( R \), find the value of \( R \).
A
5
B
7
C
9
D
11

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