Mathematics
Number System
Find the HCF (GCD) of 238 and 153.
A. 18
B. 34
C. 8
D. 17
Correct Answer: D
The greatest common divisor of 238 and 153 is 17.
Mathematics
Number System
A two-digit number is 81. What is the absolute difference between the number and the number formed by reversing its digits?
A. 7
B. 72
C. 54
D. 63
Correct Answer: D
Reversed number = 18. Absolute difference = |81 - 18| = 63.
Mathematics
Number System
What is the greatest multiple of 33 that is less than 1469?
A. 1453
B. 1485
C. 1452
D. 1419
Correct Answer: C
1469 ÷ 33 has integer quotient 44; 33 × 44 = 1452.
Mathematics
Number System
The sum of 3 consecutive integers is 27. What is the middle integer?
A. 8
B. 9
C. 10
D. 12
Correct Answer: B
The middle integer equals the average: 27 ÷ 3 = 9.
Mathematics
Number System
Find the next number: 2, 7, 13, 20, 28, ?
A. 37
B. 38
C. 36
D. 33
Correct Answer: A
The differences are 5, 6, 7, 8, increasing by 1. The next difference is 9, so the answer is 37.
Mathematics
Number System
Find the next term in the series: 45, 72, 105, 144, 189, ?
A. 234
B. 285
C. 240
D. 246
Correct Answer: C
The first differences are [27, 33, 39, 45]; their second difference is constant at 6. Continuing the pattern gives 240.
Mathematics
Number System
Find the next term in the series: 20, 29, 40, 53, 68, ?
A. 85
B. 100
C. 83
D. 87
Correct Answer: A
The first differences are [9, 11, 13, 15]; their second difference is constant at 2. Continuing the pattern gives 85.
Mathematics
Number System
What least number must be added to 1961 so that the result is exactly divisible by 19?
A. 4
B. 15
C. 16
D. 34
Correct Answer: B
1961 leaves remainder 4 on division by 19. Add 19 - 4 = 15.
Mathematics
Number System
How many integers from 100 to 336, inclusive, are divisible by 6?
A. 56
B. 41
C. 39
D. 40
Correct Answer: D
Count = ⌊336/6⌋ - ⌊(100-1)/6⌋ = 56 - 16 = 40.
Mathematics
Number System
Find the next number in the series: 54, 66, 78, 90, 102, ?
A. 114
B. 126
C. 102
D. 138
Correct Answer: A
The common difference is 12. So the next term is 102 + 12 = 114.
Mathematics
Number System
The sum of 3 consecutive integers is 150. What is the middle integer?
A. 53
B. 51
C. 49
D. 50
Correct Answer: D
The middle integer equals the average: 150 ÷ 3 = 50.
Mathematics
Number System
Find the next number: 16, 21, 30, 43, 60, ?
A. 85
B. 77
C. 81
D. 65
Correct Answer: C
The differences are 5, 9, 13, 17, increasing by 4. The next difference is 21, so the answer is 81.
Mathematics
Number System
Find the next number: 1, 9, 25, 57, 121, ?
A. 256
B. 249
C. 247
D. 242
Correct Answer: B
Each term is obtained by ×2 + 7. So 121 × 2 + 7 = 249.
Mathematics
Number System
What is the least positive number exactly divisible by 10, 17, and 15?
A. 1020
B. 510
C. 520
D. 17
Correct Answer: B
The required number is LCM(10, 17, 15) = 510.
Mathematics
Number System
Find the next number in the series: 16, 22, 28, 34, 40, ?
A. 58
B. 40
C. 46
D. 52
Correct Answer: C
The common difference is 6. So the next term is 40 + 6 = 46.
Mathematics
Number System
Find the next number: 1, 6, 16, 36, 76, ?
A. 156
B. 152
C. 160
D. 154
Correct Answer: A
Each term is obtained by ×2 + 4. So 76 × 2 + 4 = 156.
Mathematics
Number System
Find the next term: 14, 24, 38, 62, 100, 162, ?
A. 262
B. 200
C. 324
D. 300
Correct Answer: A
Each term is the sum of the previous two. Therefore 100 + 162 = 262.
Mathematics
Number System
Classify 31/21.
A. Whole number
B. Rational
C. Irrational
D. Prime number
Correct Answer: B
31/21 is a ratio of two integers with a non-zero denominator, so it is rational.
Mathematics
Number System
Find the missing number: 41, 53, ?, 77, 89, 101
A. 53
B. 77
C. 89
D. 65
Correct Answer: D
This is an arithmetic series with common difference 12; the missing term is 65.
Mathematics
Number System
What is the remainder when 1639 is divided by 24?
A. 7
B. 9
C. 8
D. 10
Correct Answer: A
1639 = 24 × 68 + 7; therefore the remainder is 7.