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

Given digits 2, 2, 3, 3, 4, 4, 4, 4 how many distinct 4 digit numbers greater than 3000 can be formed?

  1. 50

  2. 51

  3. 52

  4. 54
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

With digits 2,2,3,3,4,4,4,4, we need 4-digit numbers > 3000. Case 1 (Thousand digit = 3): Hundred digit can be 2,3,4. If hundred=2: tens can be 2,3,4; units accordingly. If hundred=3: tens can be 2,3,4. If hundred=4: tens can be 2,3,4. Case 2 (Thousand digit = 4): Hundred can be 2,3,4 with similar arrangements. Total distinct arrangements = 51.

Multiple choice

The binary language consists of _________ digit(s).

  1. 8

  2. 2

  3. 1,000

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

Binary is a base-2 number system that uses only two digits: 0 and 1. This is the fundamental language of digital computers because electronic circuits can easily represent two states (on/off). Decimal uses 10 digits, not relevant to binary.

Multiple choice

In a three digit number, the hundreds digit is 2 more than the tens digit and the units digit is 2 less than the tens digit. If the sum of the digits is 18, find the number.

  1. 975

  2. 753

  3. 642

  4. None of these

  5. 684
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the three digit numbers be 100a + 10b + c.  a = b + 2 c = b - 2 a + b + c = 3b =18 b = 6, so a = 8 and c = 4. Hence, the three digit number is 864. In this question, the hundreds digit is 2 less than the tens digit and the tens digit is 4 more than the ones digit which does not match the requirement of the question. So, it cannot be the answer.

Multiple choice

Which digit is at hundred thousands place in 527472?

  1. 2

  2. 4

  3. 5

  4. 7
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

52747 ||||||| |---|---|---|---|---|---| |

Hundred thousands
|
Ten thousands
|
Thousands
|
Hundreds
|
Tens
|
Units
| |
          5
|
     2
|
    7
|
    4
|
  7
|
  2
|

5 is at hundred thousands place.

Multiple choice

Which digit is at ten thousands place in 937950?

  1. 3

  2. 5

  3. 7

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

93795 ||||||| |---|---|---|---|---|---| |

Hundred thousands
|
Ten thousands
|
Thousands
|
Hundreds
|
Tens
|
Units
| |
        9
|
        3
|
     7
|
    9
|
   5
|
   0
|  
3 is at ten thousands place.