Quantitative Aptitude

Number System and Simplification

585 Questions

Number system and simplification questions assess mathematical proficiency in handling fractions, decimals, and complex algebraic expressions. Test takers must simplify surds, calculate reciprocals, and solve intricate number pattern equations. This foundational quantitative aptitude topic is critical for achieving high scores in SSC and banking exams.

Fraction simplificationDecimal operationsSurds and indicesPercentage calculationsComplex number algebra

Number System and Simplification Questions

Multiple choice

Use the Möbius Inversion Formula to find a formula for the sum of the divisors of an integer ( n ).

  1. \( \sum_{d|n} d = n \)
  2. \( \sum_{d|n} d = \phi(n) \)
  3. \( \sum_{d|n} d = \sigma(n) \)
  4. \( \sum_{d|n} d = \mu(n) \)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the Möbius Inversion Formula with ( f(n) = d ) and ( g(n) = \sum_{d|n} \mu(d) d ), we get ( d = \sum_{d|n} \mu(d) g(\frac{n}{d}) ). Since ( g(\frac{n}{d}) = \sigma(\frac{n}{d}) ) for all ( d | n ), we have ( \sum_{d|n} d = \sigma(n) ).

Multiple choice

Use the Möbius Inversion Formula to find a formula for the sum of the Möbius function over the divisors of a square-free integer ( n ).

  1. \( \sum_{d|n} \mu(d) = 1 \)
  2. \( \sum_{d|n} \mu(d) = n \)
  3. \( \sum_{d|n} \mu(d) = \phi(n) \)
  4. \( \sum_{d|n} \mu(d) = \sigma(n) \)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since ( n ) is square-free, all of its divisors are also square-free. Therefore, ( \mu(d) = 1 ) for all ( d | n ). Using the Möbius Inversion Formula with ( f(n) = 1 ) and ( g(n) = \sum_{d|n} \mu(d) ), we get ( 1 = \sum_{d|n} \mu(d) g(\frac{n}{d}) ). Since ( g(\frac{n}{d}) = 1 ) for all ( d | n ), we have ( \sum_{d|n} \mu(d) = 1 ).

Multiple choice

Use the Möbius Inversion Formula to find a formula for the sum of the Möbius function over the divisors of an integer ( n ) that is divisible by ( m ).

  1. \( \sum_{d|n} \mu(d) = 1 \)
  2. \( \sum_{d|n} \mu(d) = n \)
  3. \( \sum_{d|n} \mu(d) = \phi(n) \)
  4. \( \sum_{d|n} \mu(d) = \sigma(n) \)
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

If ( m ) is divisible by ( n ), then all of the divisors of ( n ) that are divisible by ( m ) are also divisible by ( \frac{n}{m} ). Therefore, ( \mu(d) = 0 ) for all ( d | n ) that are divisible by ( m ). Using the Möbius Inversion Formula with ( f(n) = 1 ) and ( g(n) = \sum_{d|n} \mu(d) ), we get ( 1 = \sum_{d|n} \mu(d) g(\frac{n}{d}) ). Since ( g(\frac{n}{d}) = 0 ) for all ( d | n ) that are divisible by ( m ), we have ( \sum_{d|n} \mu(d) = \begin{cases} 1 & \text{if } m = 1 \ 0 & \text{if } m > 1 \end{cases} ).

Multiple choice

Use the Möbius Inversion Formula to find a formula for the sum of the Möbius function over the divisors of an integer ( n ) that is not divisible by ( m ).

  1. \( \sum_{d|n} \mu(d) = 1 \)
  2. \( \sum_{d|n} \mu(d) = n \)
  3. \( \sum_{d|n} \mu(d) = \phi(n) \)
  4. \( \sum_{d|n} \mu(d) = \sigma(n) \)
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

If ( m ) is not divisible by ( n ), then there is at least one prime factor of ( n ) that is not a prime factor of ( m ). Therefore, there is at least one divisor of ( n ) that is not divisible by ( m ). Since ( \mu(d) = 0 ) for all ( d | n ) that are divisible by ( m ), we have ( \sum_{d|n} \mu(d) = -1 ). Using the Möbius Inversion Formula with ( f(n) = 1 ) and ( g(n) = \sum_{d|n} \mu(d) ), we get ( 1 = \sum_{d|n} \mu(d) g(\frac{n}{d}) ). Since ( g(\frac{n}{d}) = -1 ) for all ( d | n ) that are not divisible by ( m ), we have ( \sum_{d|n} \mu(d) = \begin{cases} 0 & \text{if } m = 1 \ -1 & \text{if } m > 1 \end{cases} ).

Multiple choice

Use the Möbius Inversion Formula to find a formula for the sum of the Möbius function over the divisors of an integer ( n ) that are not relatively prime to ( n ).

  1. \( \sum_{d|n} \mu(d) = 1 \)
  2. \( \sum_{d|n} \mu(d) = n \)
  3. \( \sum_{d|n} \mu(d) = \phi(n) \)
  4. \( \sum_{d|n} \mu(d) = \sigma(n) \)
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

If ( d ) is a divisor of ( n ) that is not relatively prime to ( n ), then there is at least one prime factor of ( n ) that is also a prime factor of ( d ). Therefore, ( \mu(d) = 0 ). Using the Möbius Inversion Formula with ( f(n) = 1 ) and ( g(n) = \sum_{d|n} \mu(d) ), we get ( 1 = \sum_{d|n} \mu(d) g(\frac{n}{d}) ). Since ( g(\frac{n}{d}) = 0 ) for all ( d | n ) that are not relatively prime to ( n ), we have ( \sum_{d|n} \mu(d) = 0 ).

Multiple choice

What is the Brahmagupta formula?

  1. $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$
  2. $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$
  3. $x = \frac{-b \pm \sqrt{b^2 + 4ac}}{2a}$
  4. $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{4a}$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

The Brahmagupta formula is given by the equation $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$, where $a$, $b$, and $c$ are the coefficients of the quadratic equation $ax^2 + bx + c = 0$.

Multiple choice

What is the general formula for the Madhava series for the arctangent function?

  1. $$\arctan x = x - \frac{x^3}{3} + \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$
  2. $$\arctan x = x - \frac{x^3}{3!} + \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$
  3. $$\arctan x = x - \frac{x^3}{3} + \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$
  4. $$\arctan x = x - \frac{x^3}{3!} + \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

The general formula for the Madhava series for the arctangent function is $$\arctan x = x - \frac{x^3}{3} + \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$.

Multiple choice

What is the general formula for the Madhava series for pi?

  1. $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
  2. $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
  3. $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
  4. $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

The general formula for the Madhava series for pi is $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$.

Multiple choice

What is the value of the following expression: (\frac{1}{2} + \frac{1}{3} + \frac{1}{6})?

  1. \(\frac{11}{6}\)
  2. \(\frac{5}{6}\)
  3. \(\frac{7}{6}\)
  4. \(\frac{9}{6}\)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To find the value of the expression, we can add the fractions as follows: (\frac{1}{2} + \frac{1}{3} + \frac{1}{6} = \frac{3}{6} + \frac{2}{6} + \frac{1}{6} = \frac{6}{6} = \frac{11}{6}).

Multiple choice

What is the general formula for the Madhava series for the arctangent function?

  1. $$arctan(x) = x - \frac{x^3}{3} + \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$
  2. $$arctan(x) = x + \frac{x^3}{3} + \frac{x^5}{5} + \frac{x^7}{7} + \cdots$$
  3. $$arctan(x) = x - \frac{x^3}{3} - \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$
  4. $$arctan(x) = x + \frac{x^3}{3} - \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The general formula for the Madhava series for the arctangent function is $$arctan(x) = x - \frac{x^3}{3} + \frac{x^5}{5} - \frac{x^7}{7} + \cdots$$. This series converges for all values of x between -1 and 1.

Multiple choice

What is the general formula for the Madhava series for pi?

  1. $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
  2. $$\pi = 4 \left(1 + \frac{1}{3} + \frac{1}{5} + \frac{1}{7} + \cdots\right)$$
  3. $$\pi = 4 \left(1 - \frac{1}{3} - \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
  4. $$\pi = 4 \left(1 + \frac{1}{3} - \frac{1}{5} - \frac{1}{7} + \cdots\right)$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The general formula for the Madhava series for pi is $$\pi = 4 \left(1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \cdots\right)$$. This series converges very slowly, but it was the first series expansion for pi to be discovered.

Multiple choice

The equation (\frac{a}{b} = \frac{c}{d}) is known as:

  1. Pythagorean theorem

  2. Euler's formula

  3. Cross-multiplication rule

  4. Law of sines

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The equation (\frac{a}{b} = \frac{c}{d}) is known as the cross-multiplication rule, which is used to solve proportions.

Multiple choice

In modular arithmetic, what is the value of 7^3 mod 5?

  1. 1

  2. 2

  3. 3

  4. 4

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Modular arithmetic involves calculations with integers modulo a fixed integer. In this case, we are working modulo 5. To find 7^3 mod 5, we can calculate 7^3 = 343, and then divide it by 5 to get the remainder. 343 ÷ 5 = 68 remainder 3. Therefore, 7^3 mod 5 = 3.

Multiple choice

What is the value of the Gamma function at (\frac{1}{2})?

  1. $\sqrt{\pi}$
  2. $\frac{1}{\sqrt{\pi}}$
  3. $\frac{\pi}{2}$
  4. $\frac{2}{\pi}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Gamma function at (\frac{1}{2}) is equal to (\sqrt{\pi}).

Multiple choice

What is the value of the Gamma function at (\frac{3}{2})?

  1. $\frac{\sqrt{\pi}}{2}$
  2. $\frac{2}{\sqrt{\pi}}$
  3. $\frac{\pi}{2}$
  4. $\frac{3\sqrt{\pi}}{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Gamma function at (\frac{3}{2}) is equal to (\frac{\sqrt{\pi}}{2}).