Practice questions

Aptitude practice questions (Group 4)

Questions 1 to 5 of 20

By TNPSC Guide editorial team · Last updated: 27.10.2026

1. Question 1

   Consider the following statements on perfect squares. 1. A perfect square that ends in zero ends in an odd number of zeros. 2. A perfect square divided by 3 never leaves remainder 2. 3. A perfect square divided by 4 leaves remainder 0 or 1. Which of these are correct?

   1. A. 2 only
   2. B. 1 and 2 only
   3. C. 2 and 3 only
   4. D. 1, 2 and 3
   Answer and explanation

   Correct answer: C. 2 and 3 only

   A square ending in zero ends in an even number of zeros (2500, 10000); a perfect square leaves 0 or 1 on division by 3 and 0 or 1 on division by 4; so 2 and 3 are correct and 1 is wrong.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 1 எண்கள், p. 28 (PDF p. 34))

2. Question 2

   Assertion [A]: 10 − 2 + 3 = 11. Reason [R]: Although A (addition) is written before S (subtraction) in BIDMAS, addition and subtraction are done from left to right.

   1. A. Both [A] and [R] are true and [R] is the correct explanation of [A]
   2. B. Both [A] and [R] are true but [R] is not the correct explanation of [A]
   3. C. [A] is true but [R] is false
   4. D. [A] is false but [R] is true
   Answer and explanation

   Correct answer: A. Both [A] and [R] are true and [R] is the correct explanation of [A]

   BIDMAS is worked from left to right: 10 − 2 + 3 = 8 + 3 = 11; doing 10 − 5 = 5 is wrong; so both are true and [R] explains [A].

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 1 எண்கள் (1.7 செயலிகளின் வரிசை), p. 17 (PDF p. 21))

3. Question 3

   What is the difference between the values of 5 × (6 + 2) and (5 × 6) + 2?

   1. A. 0
   2. B. 8
   3. C. 2
   4. D. 10
   Answer and explanation

   Correct answer: B. 8

   5 × (6 + 2) = 5 × 8 = 40 and (5 × 6) + 2 = 30 + 2 = 32; the difference is 40 − 32 = 8; putting brackets in the right place avoids confusion.

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 1 எண்கள் (1.7 செயலிகளின் வரிசை), pp. 16-17 (PDF pp. 20-21))

4. Question 4

   Consider the following statements on successive percentage changes. 1. Increasing a number by 25% and then decreasing it by 20% leaves it unchanged. 2. An income that rises by 10% and then falls by 10% is unchanged. 3. If P's income is 50% more than Q's, then Q's income is 33⅓% less than P's. Which of these are correct?

   1. A. 1 only
   2. B. 1 and 2 only
   3. C. 1 and 3 only
   4. D. 1, 2 and 3
   Answer and explanation

   Correct answer: C. 1 and 3 only

   25 − 20 − 25 × 20/100 = 0, so 1 is correct; 10 − 10 − 10 × 10/100 = −1, a 1% decrease, so 2 is wrong; with Q = 100, P = 150 and 50/150 × 100 = 33⅓%, so 3 is correct.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (விடைகள் (பயிற்சி 4.1, 4.2, 4.5), p. 286 (PDF p. 292))

5. Question 5

   Write 45% as a fraction in its lowest form.

   1. A. 9/20
   2. B. 45/10
   3. C. 4/5
   4. D. 9/2
   Answer and explanation

   Correct answer: A. 9/20

   Per cent means per hundred; x% = x/100: 45% = 45/100 = 9/20.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 4 வாழ்வியல் கணிதம், p. 128 (PDF p. 134))