Quantitative Aptitude

Number System and Digits

380 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 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.

Multiple choice

What is the place value notation used in the Indian Number System?

  1. Units, tens, hundreds, thousands, and so on.

  2. Ones, tens, hundreds, thousands, and so on.

  3. Digits, tens, hundreds, thousands, and so on.

  4. Numbers, tens, hundreds, thousands, and so on.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The place value notation in the Indian Number System uses the concept of ones, tens, hundreds, thousands, and so on, to represent numbers.

Multiple choice

What is the place value of the digit '3' in the number 3456?

  1. 3

  2. 30

  3. 300

  4. 3000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The place value of a digit indicates the value it represents based on its position in a number. In the number 3456, the digit '3' is in the hundreds place, so its place value is 300.

Multiple choice

In the number 2045, what is the value of the digit '0'?

  1. 0

  2. 10

  3. 100

  4. 1000
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The digit '0' in the number 2045 holds the place value of the tens. However, since there is no digit in the tens place, its value is 0.

Multiple choice

What is the smallest 4-digit number that can be formed using the digits 1, 2, 3, and 4?

  1. 1234

  2. 1324

  3. 1423

  4. 2134
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To form the smallest 4-digit number, arrange the digits in ascending order from left to right. Therefore, the smallest 4-digit number is 1234.

Multiple choice

What is the sum of the digits in the number 7894?

  1. 18

  2. 27

  3. 36

  4. 45
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

To find the sum of the digits, add the individual digits of the number. 7 + 8 + 9 + 4 = 28.

Multiple choice

Which of the following numbers is the product of its digits?

  1. 123

  2. 234

  3. 345

  4. 456
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The product of the digits of a number is found by multiplying all its digits together. In this case, 1 x 2 x 3 = 6, so 123 is the only number whose digits multiply to give 6.

Multiple choice

Which Vedic Sutra enables rapid multiplication of two large numbers?

  1. Nikhilam Navatashcaramam Dashatah

  2. Urdhva Tiryakbhyam

  3. Ekadhikina Purvena

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

The Urdhva Tiryakbhyam Sutra is a powerful Vedic technique for multiplying two numbers. It involves multiplying the digits of the numbers in a vertical and crosswise manner, resulting in a quick and efficient multiplication process.

Multiple choice

How many 4-digit numbers can be formed using the digits 1, 2, 3, 4, and 5 if repetition of digits is not allowed?

  1. 120

  2. 600

  3. 24

  4. 3600
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To calculate the number of 4-digit numbers that can be formed using the digits 1, 2, 3, 4, and 5 without repetition, we use the formula nPr = n! / (n - r)!, where n is the total number of items and r is the number of items to be chosen. In this case, n = 5 and r = 4. Therefore, the number of 4-digit numbers that can be formed using the digits 1, 2, 3, 4, and 5 without repetition is 5P4 = 5! / (5 - 4)! = 3600.

Multiple choice

How many 5-digit numbers can be formed using the digits 0, 1, 2, 3, and 4 if repetition of digits is allowed?

  1. 10000

  2. 50000

  3. 25000

  4. 125000
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To calculate the number of 5-digit numbers that can be formed using the digits 0, 1, 2, 3, and 4 with repetition allowed, we use the formula n^r, where n is the number of digits and r is the number of digits in the number. In this case, n = 5 and r = 5. Therefore, the number of 5-digit numbers that can be formed using the digits 0, 1, 2, 3, and 4 with repetition allowed is 5^5 = 125000.

Multiple choice

In the number 4050, what is the difference between the place value of the digit 4 and the place value of the digit 0?

  1. 10

  2. 100

  3. 1000

  4. 10000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the number 4050, the digit 4 is in the thousands place, while the digit 0 is in the hundreds place. The difference between their place values is 1000.