வெல்லுங்கள் CSAT 2025 - 26: Mathemetical Operations

Questions & Answers- (Multiple Choice) - MATHEMATICAL OPERATIONS
கொள்குறி வினா- விடைகள் - கணிதக் குறியீடுகள்

1 - 2 : In each of the questions given below, two signs in each equation have been interchanged. Find out these two signs to make the equation correct.

1. 4 ÷ 6 × 8 + 2 - 13 = 15
a. ÷ and + b. ÷ and -
c. - and + d. - and ×

2. 165 ÷ 3 + 14 ×3 - 19 = 12
a. ÷ and + b. - and ×
c. - and + d. ÷ and ×

3. Find the value of
56 ÷ 8 + 7 × 6 ÷ 3 - 81 ÷9
a. 18 b. 16
c. 12 d. 10

4. {6 - (15 - 7) + 64 ÷ 4 ×3 - 7}
a. 64 b. 32
c. 48 d. 39

5 - 6 : If P denotes ÷ , Q denotes ×, R denotes + and S denotes - then choose the correct value of the following questions.

5. 36 Q 24 P 8 R 5 S 6 ?
a. 108 b. 107
c. 124 d. 214

6. 28 P 7 Q 56 S 14 R 7
a. 112 b. 252
c. 214 d. 217

7 - 8 Directions : If + means ×, - means +, × means ÷ and ÷ means - , then answer the following questions based on the information.

7. 15 × 5 ÷ 3 + 3 - 3 = ?
a. - 1 b. 25
c. 2 d. 3

8. 6 - 9 + 8 ×4 - 15 = ?
a. 9 b. 14
c. 7 d. 12

9 - 10 : For the following questions
π means ' is greater than '
∆ means ' is less than '
© means ' is equal to '
× means ' plus '
= mean ' minus '

9. If p π r and q×s©r and p,q,r,and s
are >0 , then
a. s π p b. s ∆ p
c. p ∆ s d. q π r

10. If p = q ∆ r = s and p © r and p,q,r,and s are >0 , then
a. s π p b. q ∆ s
c. q π s d. r π s

11 - 12 : If the given interchanges are made in signs and numbers, choose the correct equaion among the four equations.

11. Given interchanges : signs + and × ; numbers 3 and 7
a. 23 × 17 + 37 = 428
b. 27 + 13 × 73 = 1241
c. 37 + 73 × 12 = 112
d. 23 + 17 × 73 = 388

12. Given interchanges : signs + and × ; numbers 5 and 2
a. 25 × 17 + 52 = 477
b. 25 + 17 × 52 = 909
c. 52 + 17 × 25 = 477
d. 52 × 17 + 25 = 677

13. 12^3 - 9^3 + 6^2 - 3^2 = ?
a. 1188 b. 1026
c. 1128 d. 1126

14. Which one of the four interchanges signs and numbers would make the given equation correct?
4×6 +7 = 34
a. + and × , 6 and 7
b. + and ×, 4 and 7
c. + and × , 4 and 6
d. None of these.

15. If 93 × 42 = 18 ; 76 × 38 = 24 and
59 × 26 = 22, then 45 × 68 = ?
a. 34 b. 22
c. 20 d. 23

16. If 8 * 2 @ 3 = 12 , 27 * 9 @ 4 =12, then what will be the value of
48 * 6 @ 5 ?
a. 40 b. 18
c. 78 d. 24

17. If 987 = 6 , 654 = 3 , 432 = 1 then what is the value of 897?
a. 5 b. 8
c. 6 d. 10

18 - 20 : In a certain code, the symbol for 0 (zero) is * and for 1 is $. There are no other symbols for other numbers greater than 1. But written using these two symbols only. The value of the symbol fir 1 doubles itself everytime it shifts one place to left and thus
2 is written as $* ; 3 is written as $$ ;
4 is written as $** and so on.

18. If $$$* is added to $$$, what will be the sum?
a. $$*$* b. $**$*
c. $*$*$ d. $$$*$

19. Which of the following represent 31?
a. $$$$* b. $$*$*
c. $$$*$ d. $$$$$

20. If $**** is divided by $**, what will be the result?
a. $** b. $*
c. $$* d. $$$

Answers
1. a 2. b 3. c 4. d 5. b

6. d 7. c 8. a 9. b 10. c

11. d 12. a 13. b 14. c 15. d

16. a 17. b 18. c 19. d 20. a

Explanation to Answers

1. Using option ' a ',
4 + 6 × 8 ÷ 2 - 13
= 4 + 6 × 4 - 13
= 4 + 24 - 13 = 15.
So first option is correct.

2. Using option ' a ',
165 + 3 ÷14 × 3 - 19
= 165 + 14 - 19 = 160
Using option ' b ',
165 ÷ 3 + 14 - 3 × 19
= 55 + 14 - 57 = 12.
So second option ' b ' is correct.

3. In these type of problems, we use
B O D M A S - Rule. The hierarchy should be maintained.
B - Brackets ; O - of ; D - Division ;
M - Multiplication ; A - Addition ;
S - Subtraction.
56 ÷ 8 + 7 × 6 ÷ 3 - 81 ÷9
= 7 + 7 × 2 - 9
= 7 + 14 - 9 = 12.

4. {6 - (15 - 7) + 64 ÷ 4 ×3 - 7}
= {6 - (8) + 16 ×3 - 7}
= { - 2 + 48 - 7} = 39

5. 36 × 24 ÷ 8 + 5 - 6
= 36 × 3 + 5 - 6
= 108 + 5 - 6 = 107

6. 28 P 7 Q 56 S 14 R 7
= 28 ÷ 7 × 56 - 14 + 7
= 4 × 56 - 14 +7
= 224 - 14 + 7 = 217

7. 15 × 5 ÷ 3 + 3 - 8
= 15 ÷ 5 - 3 ×3 +8
= 3 - 9 + 8 = 11 - 9 = 2

8. 6 - 9 + 8 × 4 ÷ 15
= 6 + 9 × 8 ÷ 4 - 15
= 6 + 9 × 2 - 15
= 6 + 18 - 15 = 9

9. p π r => p > r => r < p
q×s©r => q + s = r => q < r and s < r
s < r => s < p

10. p = q ∆ r = s => p - q < r - s
p © r => p = r
Combining, we get - q < - s => q > s

11. a.27 +13 × 73 = 27 + 949 = 976
b. 23 × 17 + 37 = 391 + 37 = 428
c. 73 × 37 + 12 = 2701 + 12 = 2713
d. 27 × 13 + 37 = 351+37 = 388
The choice d is correct.

12. 52 + 17 × 25 = 477
Here first one itself is correct choice.

13. 12^3 = 12×12×12 = 1728
9^3 = 9 × 9 × 9 = 729
6^2 = 6 × 6 = 36 & 3^2 = 3×3 = 9
So 12^3 - 9^3 + 6^2 - 3^2
= 1728 - 729 + 36 - 9
= 1026

14. By inspection using 'c'
6 + 4 × 7 = 6 + 28 = 34.

15. 93 × 42 = 18 => 9+3 +4+2 = 18
76 × 38 = 24 => 7+6 +3+8 = 24 and
59 × 26 = 22 => 5+9 +2+6 = 22.
So 45 × 68 => 4 + 5 + 6 + 8 = 23

16. 8 * 2 @ 3 = 12 = > 8 ÷ 2 × 3 = 12 and
27 * 9 @ 4 =12 => 27 ÷ 9 ×4 = 12
So 48 * 6 @ 5 = 48 ÷ 6 × 5 = 8 × 5 = 40.

17. 987 = 6 => - 9 + 8 + 7 = 6
654 = 3 = > - 6 + 5 + 4 = 3
432 = 1 => - 4 + 3 + 2 = 1
So 897 = - 8 + 9 + 7 = 8.

18. $$$*, In this binary code
1110 => 2^3 + 2^2 +2^1 +0
= 8+4+2 = 14.
$$$, In this binary code
111 => 2^2 + 2^1 +2^0 = 4+2+1 =7
So $$$* + $$$ = 14 + 7 =21
21, In the binary code
16 + 4 +1 = 2^4 + 2^2 + 2^0
Code $*$*$

19. Clearly $$$$$ => 11111
=> 2^4 + 2^3 + 2^2 + 2^1 + 2^0
=> 16 + 8 + 4 + 2 + 1 = 31.

20. $**** => 10000 => 2^4 = 16
$** => 100 => 2^2 = 4
But 16 ÷ 4 = 4 .
The binary code for 4 is 100 => $**

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