Quantitative Aptitude

Number System and Digits

374 Questions

Number system and digits questions test the ability to manipulate numbers, identify significant digits, and form specific values. These problems often require finding missing digits or determining the properties of large sums. They form a vital component of the quantitative aptitude section.

Number formationMissing digitsSignificant digitsLargest and smallest numbersDigit sum properties

Number System and Digits Questions

Multiple choice maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

The unit's digit in the product $274 \times 318 \times 577 \times 313$ is:

  1. 2

  2. 3

  3. 4

  4. 5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$ The\quad units\quad place\quad numbers\quad are\quad 4,\quad 8,\quad 7\quad and\quad 3.\ 4\times 8=32\longrightarrow \quad units\quad place\quad number\quad is\quad 2\ 2\times 7=14\longrightarrow \quad units\quad place\quad number\quad is\quad 4\ 4\times 3=12\longrightarrow \quad units\quad place\quad number\quad is\quad 2\ Answer-\quad Option\quad A $

Multiple choice maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

In the correctly worked out multiplication problem at the below, each letter represent a different digit. What is the value of B ?

A A
A B

   B B
A A C

A 3 B

  1. 1

  2. 2

  3. 4

  4. 5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$B + C = B$

$C = 0$

AA.B $=$ BB $\Rightarrow $ (10 A + A) B $ = $BB= 10 B $+$ B

$AB = B,A = 1$

$ B+A = 3 $

$\Rightarrow B + 1 =3, \Rightarrow B = 2$

1 1 

11

12

22

110

132

Multiple choice

What digit does not exist in Roman Numerals

  1. 1000

  2. 1 million

  3. Zero

  4. -1
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Roman numerals are based on letters (I, V, X, L, C, D, M) and do not include a symbol for zero, as the concept was not part of the Roman number system.

Multiple choice maths multiplication and division of algebraic expressions linear and synthetic method of division factorising expressions using factor theorem division algorithm for polynomials

The sum of the digits of a 3 digit number is subtracted from the number. The resulting number is always.

  1. Divisible by 6

  2. Not divisible by 6

  3. Divisible by 9

  4. Not divisible by 9
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the no. be $xyz$ sum of digit is $(x+y+z)$ 

as $xyz=100x+10y+z$
then $xyz-(x+y+z)=99x+9y$  
$\therefore $ $\boxed{Always\, divisible\, by\, 9}$