Question 1

The sum of the first 5 natural numbers is:

Accepted Answer

Correct Answer: 15

Explanation: The first 5 natural numbers are 1, 2, 3, 4, 5. Adding them: 1 + 2 = 3; 3 + 3 = 6; 6 + 4 = 10; 10 + 5 = 15. Alternatively, use the formula n(n+1)/2 where n=5. 5(6)/2 = 30/2 = 15. This formula is useful for larger series.

Question 2

What is the LCM of 4 and 6?

Accepted Answer

Correct Answer: 12

Explanation: LCM (Least Common Multiple) is the smallest number that is divisible by both numbers. Multiples of 4: 4, 8, 12, 16... Multiples of 6: 6, 12, 18... The first common multiple is 12. Although 24 is also a common multiple, it is not the least.

Question 3

Convert 5000 meters to kilometers.

Accepted Answer

Correct Answer: 5 km

Explanation: There are 1000 meters in 1 kilometer. To convert meters to kilometers, divide the number of meters by 1000. 5000 / 1000 = 5. So, 5000 meters is equal to 5 kilometers. Kilo is the prefix for 1000.

Question 4

If x + y = 10 and x - y = 2, find x.

Accepted Answer

Correct Answer: 6

Explanation: Add the two equations together: (x + y) + (x - y) = 10 + 2. The y's cancel out: 2x = 12. Divide by 2: x = 6. Substituting x=6 into the first equation: 6 + y = 10, so y = 4. Thus x is 6 and y is 4.

Question 5

Which angle is a Right Angle?

Accepted Answer

Correct Answer: 90°

Explanation: A right angle is exactly 90 degrees. It corresponds to a quarter turn. Angles less than 90° are Acute, and angles between 90° and 180° are Obtuse. A 180° angle is called a Straight angle. Right angles are marked with a small square in geometry diagrams.

Question 6

Solve: 5³

Accepted Answer

Correct Answer: 125

Explanation: 5 cubed means 5 multiplied by itself three times: 5 × 5 × 5. 5 × 5 = 25. Then 25 × 5 = 125. A common mistake is multiplying base by exponent (5 × 3 = 15), which is incorrect. Exponentiation indicates repeated multiplication.

Question 7

The absolute value of -7 is:

Accepted Answer

Correct Answer: 7

Explanation: The absolute value of a number is its distance from zero on the number line, regardless of direction. It is always non-negative. The symbol is |-7|. Since distance cannot be negative, |-7| = 7. Similarly, |7| is also 7.

Question 8

10% of a number is 20. What is the number?

Accepted Answer

Correct Answer: 200

Explanation: Let the number be x. 10% of x = 20. This translates to (10/100) × x = 20. Simplifying, 0.1x = 20. Divide by 0.1: x = 20 / 0.1 = 200. Alternatively, if 10% is 20, then 100% (the full number) is 20 × 10 = 200.

Question 9

A rectangle has length 10m and width 5m. Its Perimeter is:

Accepted Answer

Correct Answer: 30 m

Explanation: Perimeter of a rectangle is calculated as P = 2(Length + Width). P = 2(10 + 5) = 2(15) = 30 m. Area would be Length × Width = 50 m². Perimeter measures the total distance around the outside of the shape.

Question 10

Which of these is an irrational number?

Accepted Answer

Correct Answer: √2

Explanation: An irrational number cannot be expressed as a simple fraction a/b. √2 is approximately 1.414... and its decimals go on forever without repeating. √4 is 2, which is rational. Integers and terminating decimals are always rational. Pi (π) is another famous irrational number.

Question 11

The value of 'x' in x/5 = 10 is:

Accepted Answer

Correct Answer: 50

Explanation: To solve for x, you need to isolate it. Since x is divided by 5, multiply both sides of the equation by 5 to cancel the denominator. x = 10 × 5. Therefore, x = 50. This is a basic algebraic operation involving multiplication property of equality.

Question 12

What comes next: 1, 4, 9, 16, 25, ...

Accepted Answer

Correct Answer: 36

Explanation: This series consists of squares of natural numbers. 1²=1, 2²=4, 3²=9, 4²=16, 5²=25. The next number should be the square of 6. 6² = 36. Recognizing squares and cubes is a standard technique for solving series questions.

Question 13

Find the simple interest on 1000 for 2 years at 5% rate.

Accepted Answer

Correct Answer: 100

Explanation: The formula for Simple Interest is SI = (P × R × T) / 100. Here, Principal (P) = 1000, Rate (R) = 5, Time (T) = 2. SI = (1000 × 5 × 2) / 100 = 10000 / 100 = 100. Simple interest is calculated only on the principal amount.

Question 14

What is the probability of getting a 'Head' in a single coin toss?

Accepted Answer

Correct Answer: 1/2

Explanation: A coin has two possible outcomes: Head (H) or Tail (T). The total number of outcomes is 2. The favorable outcome (Head) is 1. Probability = Favorable Outcomes / Total Outcomes = 1/2 or 50%. This assumes the coin is fair and unbiased.

Question 15

If 15 men can do a work in 20 days, how many days will 10 men take?

Accepted Answer

Correct Answer: 30 days

Explanation: This is an inverse proportion problem. (Men1 × Days1) = (Men2 × Days2). 15 × 20 = 10 × D2. 300 = 10 × D2. D2 = 300 / 10 = 30 days. As the number of men decreases, the time taken increases. This is the concept of 'Man-Days'.

Question 16

A polygon with 5 sides is called:

Accepted Answer

Correct Answer: Pentagon

Explanation: A Pentagon is a polygon with 5 sides and 5 angles. 'Penta' comes from Greek meaning five. A Quadrilateral has 4 sides, a Hexagon has 6 sides, and an Octagon has 8 sides. The sum of interior angles of a pentagon is 540 degrees.

Question 17

Which number is divisible by 5?

Accepted Answer

Correct Answer: 150

Explanation: The divisibility rule for 5 states that a number is divisible by 5 if its last digit (unit digit) is either 0 or 5. Looking at the options: 132 (ends in 2), 147 (ends in 7), 150 (ends in 0), 159 (ends in 9). Only 150 satisfies the condition.

Question 18

Simplify: (2 + 3) × 4

Accepted Answer

Correct Answer: 20

Explanation: According to BODMAS/PEMDAS rule, Brackets must be solved first. (2 + 3) = 5. Then perform the multiplication: 5 × 4 = 20. If you multiplied 3 × 4 first, you would get 14, which is incorrect because brackets have higher priority.

Question 19

What is the complementary angle of 30°?

Accepted Answer

Correct Answer: 60°

Explanation: Complementary angles are two angles whose sum is 90 degrees. To find the complement of 30°, subtract it from 90°. 90° - 30° = 60°. Supplementary angles sum up to 180°, which is a common point of confusion.

Question 20

How many seconds are there in 1 hour?

Accepted Answer

Correct Answer: 3600

Explanation: 1 hour has 60 minutes. 1 minute has 60 seconds. To find seconds in an hour, multiply 60 × 60. 6 × 6 = 36, and add the two zeros, resulting in 3600 seconds. This conversion is frequently used in physics and speed-time problems.

Mathematics MCQs