State Exam — Quantitative Aptitude — Numbers
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Showing 11–20 of 500 questions in Numbers
Q.11 Easy Numbers
What is the product of the first five prime numbers?
A2310
B2520
C2100
D2640
Correct Answer:  A. 2310
Explanation:

First five prime numbers are 2, 3, 5, 7, 11.

Product = 2 × 3 × 5 × 7 × 11 = 2310

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Q.12 Easy Numbers
Which of the following is a perfect square?
A145
B169
C200
D198
Correct Answer:  B. 169
Explanation:

This question asks us to identify which number is a perfect square (a number that equals an integer multiplied by itself).

Step 1: Understand Perfect Squares

A perfect square is a number that can be expressed as n × n where n is an integer.

\[\text{Perfect Square} = n^2\]
Step 2: Check Each Option

Test each option by finding if its square root is a whole number.

\[\sqrt{145} \approx 12.04, \quad \sqrt{169} = 13, \quad \sqrt{200} \approx 14.14, \quad \sqrt{198} \approx 14.07\]
Step 3: Verify the Correct Answer

Only 169 has a whole number square root.

\[13 \times 13 = 169\]

169 is a perfect square because 13 × 13 = 169, making the correct answer (B).

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Q.13 Easy Numbers
What is the difference between the largest 3-digit number and the smallest 3-digit number?
A899
B900
C899
D901
Correct Answer:  A. 899
Explanation:

Largest 3-digit number = 999, Smallest 3-digit number = 100.

Difference = 999 - 100 = 899

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Q.14 Easy Numbers
If a number is multiplied by 8 and then 15 is subtracted, the result is 49. What is the number?
A6
B8
C9
D7
Correct Answer:  B. 8
Explanation:

This question asks us to find an unknown number based on a sequence of arithmetic operations performed on it.

Step 1: Set up the equation

Let the unknown number be x. According to the problem, when x is multiplied by 8 and then 15 is subtracted, the result is 49.

\[8x - 15 = 49\]
Step 2: Isolate the variable term

Add 15 to both sides of the equation to move the constant to the right side.

\[8x - 15 + 15 = 49 + 15\]
\[8x = 64\]
Step 3: Solve for the number

Divide both sides by 8 to find the value of x.

\[x = \frac{64}{8} = 8\]

The number is 8, which corresponds to answer choice (B).

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Q.15 Easy Numbers
What is the average of the first 15 natural numbers?
A7
B8
C8.5
D9
Correct Answer:  B. 8
Explanation:

This question asks us to find the average value of the numbers 1 through 15.

Step 1: Identify the first 15 natural numbers

The first 15 natural numbers are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15.

\[\text{Natural numbers} = 1, 2, 3, ..., 15\]
Step 2: Calculate the sum of first 15 natural numbers

Use the formula for sum of first n natural numbers: \[\text{Sum} = \frac{n(n+1)}{2}\]

\[\text{Sum} = \frac{15 \times 16}{2} = \frac{240}{2} = 120\]
Step 3: Calculate the average

Average is the sum divided by the count of numbers.

\[\text{Average} = \frac{\text{Sum}}{\text{Count}} = \frac{120}{15} = 8\]

The average of the first 15 natural numbers is 8.

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Q.16 Easy Numbers
Find the remainder when 527 is divided by 15.
A2
B7
C12
D3
Correct Answer:  A. 2
Explanation:

This question asks us to find the remainder when 527 is divided by 15 using the division algorithm.

Step 1: Set up the division problem

We need to divide 527 by 15 and find what's left over.

\[527 \div 15\]
Step 2: Perform the division

Determine how many times 15 goes into 527 completely.

\[15 \times 35 = 525\]
Step 3: Calculate the remainder

Subtract the product from the original number to find the remainder.

\[527 - 525 = 2\]

The remainder when 527 is divided by 15 is 2, so the answer is (A).

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Q.17 Easy Numbers
Which number when divided by 11 gives quotient 9 and remainder 5?
A104
B98
C112
D99
Correct Answer:  A. 104
Explanation:

Using dividend = divisor × quotient + remainder: Number = 11 × 9 + 5 = 99 + 5 = 104

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Q.18 Medium Numbers
What is the digit sum of 9876543? (Keep reducing until single digit)
A40
B4
C42
D6
Correct Answer:  B. 4
Explanation:

9+8+7+6+5+4+3 = 42.

Then 4+2 = 6.

Wait, let me recalculate: Sum = 42, which reduces to 4+2=6.

The answer should be D.

Actually 9+8+7+6+5+4+3=42, 4+2=6.

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Q.19 Medium Numbers
Two numbers are in the ratio 5:7. If their sum is 120, what is the larger number?
A70
B50
C60
D80
Correct Answer:  A. 70
Explanation:

Let numbers be 5x and 7x.

Then 5x + 7x = 120, so 12x = 120, x = 10.

Larger number = 7 × 10 = 70

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Q.20 Medium Numbers
How many odd numbers are there between 10 and 30?
A9
B10
C11
D12
Correct Answer:  B. 10
Explanation:

Odd numbers between 10 and 30: 11, 13, 15, 17, 19, 21, 23, 25, 27, 29.

Count = 10

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