Number System Questions for RRB Group D: Download Free PDF

Are you working hard to get a government job in Indian Railways? For millions of students, the RRB Group D exam is the biggest chance to secure a stable life. But to clear the Computer-Based Test (CBT), you cannot run away from Mathematics. We know that many of you come from non-math backgrounds and feel nervous about calculations. But here is the good news: The Math asked in RRB Group D is very simple. It is strictly based on the Class 10th level. The best chapter to start your preparation is the Number System. It is the easiest topic because it deals with basic numbers, odd-even rules, and simple divisions. You don’t need complex formulas here. If you master this, you can easily secure 2-3 marks in just a few minutes. To help you practice without stress, we have selected the most repeated Number System questions for RRB Group D in a free PDF that you can download from this blog.

Why is the Number System Important for RRB Group D?

In the Mathematics section (25 questions), the Number System is the foundation stone.

• Easy Marks: You can expect 2 to 3 questions in every shift. These are often the easiest questions in the entire paper.
• No Big Formulas: You solve these questions using common sense logic, like “Is this number divisible by 2?” or “What is the last digit?”.
• Helps in Other Topics: If you are good at Number System, you will solve HCF-LCM and Simplification questions much faster.

Download Free PDF of Number System Questions for RRB Group D

We have prepared a comprehensive PDF containing exam-level questions. We have chosen questions that are exactly at the RRB Group D level—focusing on facts and simple logic rather than long calculations. Download it, save it, and practice these questions to build your confidence.

Q1. Find the difference between the Place Value and Face Value of 7 in the number 67432.

(a) 6993
(b) 7000
(c) 6930
(d) 7

Answer: (a) 6993

Logic:
Place Value of 7 = 7000
Face Value of 7 = 7
Difference = 7000 − 7 = 6993

Q2. Which of the following numbers is divisible by 3?

(a) 1243
(b) 1242
(c) 1244
(d) 1241

Answer: (b) 1242

Logic:
Sum of digits must be divisible by 3
1 + 2 + 4 + 2 = 9
9 is divisible by 3 → number is divisible

Q3. The product of two consecutive even numbers is 168. Find the sum of these numbers.

(a) 26
(b) 24
(c) 28
(d) 22

Answer: (a) 26

Logic:
Even numbers close to √168
√168 ≈ 13

Even numbers around 13 = 12 and 14
12 × 14 = 168

Sum = 12 + 14 = 26

Q4. What is the unit digit of 124⁴ + 124⁵ ?

(a) 0
(b) 2
(c) 4
(d) 6

Answer: (a) 0

Logic:
4 to even power ends in 6
4 to odd power ends in 4

124⁴ → last digit 6
124⁵ → last digit 4

6 + 4 = 10
Unit digit = 0

Q5. When a number is divided by 56, the remainder is 29. What will be the remainder when the same number is divided by 8?

(a) 4
(b) 5
(c) 3
(d) 7

Answer: (b) 5

Logic:
Just divide the remainder 29 by 8

29 ÷ 8 leaves remainder 5

Q6. Which is the smallest 3-digit prime number?

(a) 103
(b) 107
(c) 101
(d) 109

Answer: (c) 101

Logic:
100 is not prime
101 is not divisible by 2, 3, 5, or 7
So 101 is smallest 3-digit prime

Q7. Simplify: 0.636363… + 0.373737…

(a) 1.0101…
(b) 1.00
(c) 0.99
(d) 100/99

Answer: (a) 1.0101…

Logic:
0.636363… = 63/99
0.373737… = 37/99

63/99 + 37/99 = 100/99 = 1.0101…

Q8. The sum of the first 50 natural numbers is:

(a) 1275
(b) 1225
(c) 1250
(d) 5050

Answer: (a) 1275

Logic:
Use formula n(n+1)/2

50 × 51 / 2 = 25 × 51 = 1275

Q9. If the number 483×5 is divisible by 9, then the missing digit x is:

(a) 5
(b) 6
(c) 7
(d) 8

Answer: (c) 7

Logic:
Sum of digits = 4 + 8 + 3 + x + 5 = 20 + x
Next multiple of 9 after 20 is 27

20 + x = 27 → x = 7

Q10. What is the value of √(10 + √(25 + √121))

(a) 4
(b) 5
(c) 6
(d) 3

Answer: (a) 4

Logic:
√121 = 11
√(25 + 11) = √36 = 6
√(10 + 6) = √16 = 4

5 Preparation Tips to Master the Number System

1. Understand Place Value vs. Face Value: This is a guaranteed question in Group D. Remember: Face value is the number itself (Face never changes). Place value depends on where it sits (Units, Tens, Hundreds).
2. Master Divisibility Rules: You must know the rules for 2, 3, 4, 5, 8, 9, and 11. Most questions are simply checking if you know that for 4, you only check the last 2 digits.
3. Learn Square Roots: Memorize squares up to 25. Often, questions like sqrt(? + sqrt(?)) come, and if you know squares, you can solve them mentally without pen and paper.
4. Practice BODMAS: In simplification questions, never guess. Always follow the order: Bracket -> Division -> Multiplication -> Addition -> Subtraction.
5. Use the “Unit Digit” Trick: For big multiplication questions (like 567 x 983), don’t multiply the whole thing. Just multiply the last digits (7 x 3 = 21, so the answer ends in 1). Check the options and mark the answer.

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