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 multiplication and division vedic methods of multiplication vedic mathematics history of mathematics maths

If $31z5$ is a multiple of $9$, where $z$ is a digit, what is the value of $z$?

  1. 0

  2. 4

  3. 7

  4. 9
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Given that $31z5$ is a multiple of $9$. 

According to the divisibility rule of $9$, the sum of all the digits should be a multiple of $9$. 
Therefore, 
$3 + 1 + z + 5 = 9\ OR\ 18$
$\Rightarrow z = 9 - 9 = 0$
$\Rightarrow z = 18 - 9 = 9$

Multiple choice multiplication and division vedic methods of multiplication vedic mathematics history of mathematics maths

Find the representation of the rightmost two digits in the cubage of $96$ by Nikhilam formula of Vedic Mathematics.

  1. $100-64$
  2. $-64$
  3. $64$

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the Nikhilam cube calculation for 96, the last part is the cube of the deviation (-4)^3 = -64. To make this positive, we borrow from the previous column, resulting in 100 - 64.

Multiple choice physics units and measurement: error analysis significant figures significant figures and rounding of digits units and measurements

In the number 2.4560, there are 5 significant digits. Which one is the least significant digit?

  1. 2

  2. 4

  3. 0

  4. 6
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The least significant digit is the lowest digit in a number, located at the far right of a string.


Here 0 is the rightmost side of this number so this is least significant digit.


Option C is the correct answer

Multiple choice physics units and measurement: error analysis significant figures significant figures and rounding of digits units and measurements

Which of the following quantifies has the least number of significant digits? 

  1. $0.80760 $
  2. $0.08765$
  3. $5.7423 \times 10^2$
  4. $80.760$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The number $0.80760$ has $5$ significant digits, $0.08765$ has $4$ significant digits, $5.7423\times 10^{2}$ has $5$ significant digits and $80.760$ has $5$ significant digits.
Hence option B is correct.
Multiple choice maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

A 3-digit number 4a3 is added to another 3-digit number 984 to give the four-digit number 13b7 which is divisible by 11 Then (a + b) is

  1. 10

  2. 11

  3. 12

  4. 15
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to the question
$4 a 3 + 9 8 4 = 1 3 b 7$
$a + 8 = b$
Then$b - a = 8$
According to the question  13b7 is divisible by 11
$(7 + 3) - (b + 1) = (9 - b)$
$(9 - b) = 0$
$b = 9$
$b = 9   and   a = 1$
Then $a+b=9+1=10$

Multiple choice maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

The sum of the digit of a two digit number is $15$ and the difference between the digits is $3$. What the two digit number?

  1. $69$
  2. $78$
  3. $90$
  4. $86$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sum of digit of $2$ digit number $10x+y$ is $15$

$x+y=15$
is $3, x-y=3\x+y=15\x-y=3\----\2x=18\x=9$
So, $y=15-x\15-9\y=6$
solution can be $96$ or $69$
Answer $A$

Multiple choice

In the subtraction of two numbers, if one of the numbers is zero, what is the difference?

  1. The other number

  2. Zero

  3. The difference of the digits of the other number

  4. The product of the two numbers
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When subtracting two numbers, if one of the numbers is zero, the difference is simply the other number. This is because subtracting zero does not change the value of the other number.