Olympiad Level – Very Tricky : āĻ…āϞāĻŋāĻŽā§āĻĒāĻŋāϝāĻŧāĻžāĻĄ āĻ¸ā§āϤ⧰ – āĻ…āϤāĻŋ āϜāϟāĻŋāϞ



61. Smallest number leaving remainder 2 when divided by 3 and 4: 3 āφ⧰⧁ 4-⧰⧇ āĻšā§°āĻŖ āϕ⧰āĻŋāϞ⧇ 2 āĻ…ā§ąāĻļāĻŋāĻˇā§āϟ āĻĨāĻ•āĻž āϏ⧰⧁āϤāĻŽ āϏāĻ‚āĻ–ā§āϝāĻž āϕ⧋āύāĻŸā§‹ ?


Options: (a) 6 (b) 10 (c) 14 (d) 18


Ans: (c) 14


Explanation: The LCM of 3 and 4 is 12. Adding the remainder 2 gives 12 + 2 = 14. āĻŦā§āϝāĻžāĻ–ā§āϝāĻž: 3 āφ⧰⧁ 4-ā§° āϞ.āϏāĻž.āϗ⧁. = 12āĨ¤ āĻ…ā§ąāĻļāĻŋāĻˇā§āϟ 2 āϝ⧋āĻ— āϕ⧰āĻŋāϞ⧇ 12 + 2 = 14āĨ¤


62. HCF of co-prime numbers 14 and 25: āϏāĻšāĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž 14 āφ⧰⧁ 25-ā§° āĻ—.āϏāĻž.āϗ⧁. āĻ•āĻŋāĻŽāĻžāύ ?

Options: (a) 7 (b) 5 (c) 1 (d) 2


Ans: (c) 1


Explanation: Co-prime numbers always have HCF = 1 because they have no common factor other than 1.āĻŦā§āϝāĻžāĻ–ā§āϝāĻž: āϏāĻšāĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻžā§° āĻ—.āϏāĻž.āϗ⧁. āϏāĻĻāĻžāϝāĻŧ 1, āĻ•āĻžā§°āĻŖ āϏāĻŋāĻšāρāϤ⧰ 1-ā§° āĻŦāĻžāĻšāĻŋ⧰⧇ āφāύ āϕ⧋āύ⧋ āϏāĻžāϧāĻžā§°āĻŖ āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āύāĻžāĻĨāĻžāϕ⧇āĨ¤




63. Product of two numbers is 144 and HCF is 12. What is the LCM ? āĻĻ⧁āϟāĻž āϏāĻ‚āĻ–ā§āϝāĻžā§° āϗ⧁āĻŖāĻĢāϞ 144 āφ⧰⧁ āĻ—.āϏāĻž.āϗ⧁. 12āĨ¤ āϞ.āϏāĻž.āϗ⧁. āĻ•āĻŋāĻŽāĻžāύ ?


Options: (a) 6 (b) 12 (c) 18 (d) 24


Ans: (b) 12 


Explanation: Use the formula: Product = HCF × LCM (āĻŦā§āϝāĻžāĻ–ā§āϝāĻž: āϏ⧂āĻ¤ā§ā§°: āϗ⧁āĻŖāĻĢāϞ = āĻ—.āϏāĻž.āϗ⧁. × āϞ.āϏāĻž.āϗ⧁.)


So, āĻ…ā§°ā§āĻĨāĻžā§Ž, 144 = 12 × LCM


LCM (āϞ.āϏāĻž.āϗ⧁.)= 144 ÷ 12 = 12



64. Which number has the greatest number of factors ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ā§° āϗ⧁āĻŖāύ⧀āϝāĻŧāϕ⧰ āϏāĻ‚āĻ–ā§āϝāĻž āĻ¸ā§°ā§āĻŦāĻžāϧāĻŋāĻ• ?
Options: (a) 18 (b) 19 (c) 23 (d) 29
Ans: (a) 18
Explanation:18 has factors 1,2,3,6,9,18 (6 factors); others are prime with only 2 factors.

 

65. Smallest 3-digit number divisible by 11: 11-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āφāϟāĻžāχāϤāĻ•ā§ˆ āϏ⧰⧁ 3 āĻ…āĻ‚āϕ⧰ āϏāĻ‚āĻ–ā§āϝāĻž āϕ⧋āύāĻŸā§‹ ?
Options: (a) 100 (b) 110 (c) 121 (d) 132
Ans: (b) 110
Explanation: 11 × 10 = 110, the first 3-digit multiple.

 

66. If a number is divisible by 8, it must be divisible by: āĻāϟāĻž āϏāĻ‚āĻ–ā§āϝāĻž āϝāĻĻāĻŋ 8-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āĻšāϝāĻŧ, āϤ⧇āĻ¨ā§āϤ⧇ āϏ⧇āχāĻŸā§‹ āύāĻŋāĻļā§āϚāĻŋāϤāĻ­āĻžā§ąā§‡ āĻ•āĻŋāĻšā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āĻš'āĻŦ ?
Options: (a) 2 (b) 4 (c) Both (d) None
Ans: (c) Both
Explanation: Since 8 = 2³, it is automatically divisible by 2 and 4.

 

67. Remainder when 500 is divided by 6: 500-āĻ• 6-⧰⧇ āĻšā§°āĻŖ āϕ⧰āĻŋāϞ⧇ āĻ…ā§ąāĻļāĻŋāĻˇā§āϟ āĻ•āĻŋāĻŽāĻžāύ āĻš'āĻŦ ?
Options: (a) 1 (b) 2 (c) 3 (d) 4
Ans: (b) 2
Explanation: 6 × 83 = 498; remainder = 2.

 

68. Which is NOT a factor of 72 ? 72-ā§° āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āύāĻšāϝāĻŧ āϕ⧋āύāĻŸā§‹ ?
Options: (a) 6 (b) 8 (c) 9 (d) 10
Ans: (d) 10
Explanation: 72 is not divisible by 10.

 

69. Largest 2-digit prime: āφāϟāĻžāχāϤāĻ•ā§ˆ āĻĄāĻžāϙ⧰ ⧍ āĻ…āĻ‚āϕ⧰ āĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āϕ⧋āύāĻŸā§‹ ?
Options: (a) 97 (b) 91 (c) 89 (d) 93
Ans: (a) 97
Explanation: 97 is prime; numbers after it (98, 99) are composite.

 

70. If two numbers are multiples of 6, their HCF is always: āϝāĻĻāĻŋ āĻĻ⧁āϟāĻž āϏāĻ‚āĻ–ā§āϝāĻž 6-ā§° āϗ⧁āĻŖāĻŋāϤāĻ• āĻšāϝāĻŧ, āϤ⧇āĻ¨ā§āϤ⧇ āϏāĻŋāĻšāρāϤ⧰ āĻ—.āϏāĻž.āϗ⧁. āϏāĻĻāĻžāϝāĻŧ āĻ•āĻŋāĻŽāĻžāύ āĻš'āĻŦ ?
Options: (a) 6 (b) Multiple of 6 (c) 1 (d) 12
Ans: (b) Multiple of 6
Explanation: Both contain 6 as a factor, so HCF must include at least 6.

 

71. Which number is divisible by 99 ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ 99-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ ?
Options: (a) 198 (b) 297 (c) 396 (d) All
Ans: (d) All
Explanation: Each equals 99 × 2, 3, and 4 respectively.

 

72. Prime factorization of 100: 100-ā§° āĻŽā§ŒāϞāĻŋāĻ• āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āĻŦāĻŋāĻļā§āϞ⧇āώāĻŖ (Prime Factorization) āϕ⧋āύāĻŸā§‹ ?
Options: (a) 2²×5² (b) 4×25 (c) 10×10 (d) 20×5
Ans: (a) 2²×5²
Explanation: Only option written fully in prime factors.

 

73. Smallest number divisible by every number from 1–5: 1-ā§° āĻĒā§°āĻž 5āϞ⧈ āĻĒā§ā§°āϤāĻŋāĻŸā§‹ āϏāĻ‚āĻ–ā§āϝāĻžā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āφāϟāĻžāχāϤāĻ•ā§ˆ āϏ⧰⧁ āϏāĻ‚āĻ–ā§āϝāĻž āϕ⧋āύāĻŸā§‹ ?
Options: (a) 10 (b) 30 (c) 60 (d) 120
Ans: (c) 60
Explanation: LCM of 1,2,3,4,5 is 60.

 

74. Which number is divisible by 2,3,4,5,6 but NOT by 7 ? 2, 3, 4, 5 āφ⧰⧁ 6-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ, āĻ•āĻŋāĻ¨ā§āϤ⧁ 7-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āύāĻšā§‹ā§ąāĻž āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ āϕ⧋āύāĻŸā§‹ ?
Options: (a) 60 (b) 120 (c) 180 (d) 240
Ans: (a) 60
Explanation: 60 is divisible by all listed numbers except 7.

 

75. HCF of three consecutive numbers: āϤāĻŋāύāĻŋāϟāĻž āĻāϕ⧇⧰āĻžāĻšā§‡ āĻĨāĻ•āĻž āϏāĻ‚āĻ–ā§āϝāĻžā§° āĻ—.āϏāĻž.āϗ⧁. (HCF) āĻ•āĻŋāĻŽāĻžāύ ?
Options: (a) 1 (b) 2 (c) 3 (d) Depends
Ans: (a) 1
Explanation: Consecutive numbers share no common factor other than 1.

 

76. Which is the smallest square number divisible by 3 ? 3-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āφāϟāĻžāχāϤāĻ•ā§ˆ āϏ⧰⧁ āĻĒā§‚ā§°ā§āĻŖāĻŦā§°ā§āĻ— āϏāĻ‚āĻ–ā§āϝāĻž āϕ⧋āύāĻŸā§‹ ?
Options: (a) 3 (b) 6 (c) 9 (d) 12
Ans: (c) 9
Explanation: 3² = 9.

 

77. LCM of consecutive numbers 4 and 5: āĻāϕ⧇⧰āĻžāĻšā§‡ āĻĨāĻ•āĻž āϏāĻ‚āĻ–ā§āϝāĻž 4 āφ⧰⧁ 5-ā§° āϞ.āϏāĻž.āϗ⧁. (LCM) āĻ•āĻŋāĻŽāĻžāύ ?
Options: (a) 10 (b) 15 (c) 20 (d) 25
Explanation: Co-prime numbers → LCM = product (4×5).

 

78. Which number leaves remainder 1 when divided by any number ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹āĻ• āϝāĻŋāϕ⧋āύ⧋ āϏāĻ‚āĻ–ā§āϝāĻžā§°ā§‡ āĻšā§°āĻŖ āϕ⧰āĻŋāϞ⧇ āϏāĻĻāĻžāϝāĻŧ āĻ…ā§ąāĻļāĻŋāĻˇā§āϟ 1 āĻĨāĻžāϕ⧇ ?
Options: (a) 0 (b) 1 (c) Divisor+1 (d) Prime
Ans: (c) Divisor+1
Explanation: A number one more than the divisor always leaves remainder 1.

 

79. If a number is divisible by both 9 and 11, it is divisible by: āĻāϟāĻž āϏāĻ‚āĻ–ā§āϝāĻž āϝāĻĻāĻŋ 9 āφ⧰⧁ 11 āĻĻ⧁āϝāĻŧā§‹āϟāĻžā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āĻšāϝāĻŧ, āϤ⧇āĻ¨ā§āϤ⧇ āϏ⧇āχāĻŸā§‹ āĻ•āĻŋāĻšā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āĻš'āĻŦ ?
Options: (a) 18 (b) 99 (c) 121 (d) 100
Ans: (b) 99
Explanation: 9 and 11 are co-prime → LCM = 99.

 

80. Number of factors of 49: 49-ā§° āĻŽā§āĻ  āϗ⧁āĻŖāύ⧀āϝāĻŧāϕ⧰ āϏāĻ‚āĻ–ā§āϝāĻž āĻ•āĻŋāĻŽāĻžāύ ?
Options: (a) 2 (b) 3 (c) 4 (d) 5
Ans: (b) 3
Explanation: Factors are 1, 7, 49.

 

81. Greatest multiple of 15 less than 200: 200-āϤāĻ•ā§ˆ āϏ⧰⧁ 15-ā§° āφāϟāĻžāχāϤāĻ•ā§ˆ āĻĄāĻžāϙ⧰ āϗ⧁āĻŖāĻŋāϤāĻ• āϕ⧋āύāĻŸā§‹ ?
Options: (a) 180 (b) 195 (c) 190 (d) 175
Ans: (b) 195
Explanation:15 × 13 = 195; next is 210 (>200).

 

82. Which is divisible by 12 ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ 12-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ ?
Options: (a) 144 (b) 150 (c) 152 (d) 154
Ans: (a) 144
Explanation: Divisible by both 3 and 4.

 

83. The HCF of identical numbers is: āĻāϕ⧇ āϏāĻ‚āĻ–ā§āϝāĻž āĻĻ⧁āϟāĻžā§° āĻ—.āϏāĻž.āϗ⧁. (HCF) āĻ•āĻŋāĻŽāĻžāύ āĻšāϝāĻŧ ?
Options: (a) 1 (b) The number itself (c) 0 (d) Double
Ans: (b) The number itself
Explanation: Greatest common factor equals the number.

 

84. Which number is divisible by 15 ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ 15-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ ?
Options: (a) 45 (b) 46 (c) 47 (d) 48
Ans: (a) 45
Explanation: Must be divisible by 3 and 5.

 

85. How many factors does 1 have ? 1-ā§° āĻ•āĻŋāĻŽāĻžāύāϟāĻž āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āφāϛ⧇ ?
Options: (a) 1 (b) 2 (c) 0 (d) Infinite
Ans: (a) 1
Explanation: Only divisor is 1 itself.

 

86. Which is the smallest cube number ? āφāϟāĻžāχāϤāĻ•ā§ˆ āϏ⧰⧁ āĻĒā§‚ā§°ā§āĻŖāϘāύ āϏāĻ‚āĻ–ā§āϝāĻž (Cube Number) āϕ⧋āύāĻŸā§‹ ?
Options: (a) 1 (b) 2 (c) 4 (d) 8
Ans: (a) 1
Explanation: 1³ = 1.

 

87. If LCM is product, numbers are: āϝāĻĻāĻŋ āĻĻ⧁āϟāĻž āϏāĻ‚āĻ–ā§āϝāĻžā§° āϞ.āϏāĻž.āϗ⧁. (LCM) āϏāĻŋāĻšāρāϤ⧰ āϗ⧁āĻŖāĻĢāϞ⧰ āϏāĻŽāĻžāύ āĻšāϝāĻŧ, āϤ⧇āĻ¨ā§āϤ⧇ āϏ⧇āχ āϏāĻ‚āĻ–ā§āϝāĻž āĻĻ⧁āϟāĻž āĻ•āĻŋ ?
Options: (a) Equal (b) Co-prime (c) Even (d) Composite
Ans: (b) Co-prime
Explanation: Only co-prime numbers have LCM equal to their product.

 

88. Which is divisible by both 8 and 3 ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ 8 āφ⧰⧁ 3 āĻĻ⧁āϝāĻŧā§‹āϟāĻžā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ ?
Options: (a) 16 (b) 18 (c) 24 (d) 32
Ans: (c) 24
Explanation: LCM of 8 and 3 is 24.

 

89. Prime factors of 77: 77-ā§° āĻŽā§ŒāϞāĻŋāĻ• āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ•āϏāĻŽā§‚āĻš (Prime Factors) āϕ⧋āύāĻŦā§‹ā§° ?
Options: (a) 7 (b) 11 (c) Both (d) 3
Ans: (c) Both
Explanation: 77 = 7 × 11.

 

90. Smallest multiple of 9: 9-ā§° āφāϟāĻžāχāϤāĻ•ā§ˆ āϏ⧰⧁ āϗ⧁āĻŖāĻŋāϤāĻ• āϕ⧋āύāĻŸā§‹ ?
Options: (a) 0 (b) 9 (c) 18 (d) 27
Ans: (a) 0
Explanation: 0 is a multiple of every number (9×0=0).

 

91. Which is NOT divisible by 5 ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ 5-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āύāĻšāϝāĻŧ ?
Options: (a) 115 (b) 125 (c) 132 (d) 145
Ans: (c) 132
Explanation: Numbers divisible by 5 end in 0 or 5.

 

92. Even number divisible by 3 must be divisible by: āĻāϟāĻž āϝ⧁āĻ—ā§āĻŽ āϏāĻ‚āĻ–ā§āϝāĻž āϝāĻĻāĻŋ 3-⧰⧇ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āĻšāϝāĻŧ, āϤ⧇āĻ¨ā§āϤ⧇ āϏ⧇āχāĻŸā§‹ āύāĻŋāĻļā§āϚāĻŋāϤāĻ­āĻžā§ąā§‡ āĻ•āĻŋāĻšā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ āĻš'āĻŦ ?
Options: (a) 5 (b) 6 (c) 9 (d) 12
Ans: (b) 6
Explanation: Divisible by both 2 and 3 → divisible by 6

 

93. Smallest prime number: āφāϟāĻžāχāϤāĻ•ā§ˆ āϏ⧰⧁ āĻŽā§ŒāϞāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āϕ⧋āύāĻŸā§‹ ?
Options: (a) 0 (b) 1 (c) 2 (d) 3
Ans: (c) 2
Explanation: Prime numbers start from 2.

 

94. Which number has only one factor ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ā§° āĻ•ā§‡ā§ąāϞ āĻāϟāĻž āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āφāϛ⧇ ?
Options: (a) 0 (b) 1 (c) 2 (d) 3
Ans: (b) 1
Explanation: 1 is neither prime nor composite.

 

95. LCM of same numbers is: āĻāϕ⧇ āϏāĻ‚āĻ–ā§āϝāĻžā§° āϞ.āϏāĻž.āϗ⧁. (LCM) āĻ•āĻŋāĻŽāĻžāύ āĻšāϝāĻŧ ?
Options: (a) 1 (b) Number itself (c) Double (d) Zero
Ans: (b) Number itself
Explanation: Least common multiple equals the number.

 

96. Which is a factor of all even numbers ? āϏāĻ•āϞ⧋ āϝ⧁āĻ—ā§āĻŽ āϏāĻ‚āĻ–ā§āϝāĻžā§° āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āϕ⧋āύāĻŸā§‹ ?
Options: (a) 1 (b) 2 (c) 3 (d) 5
Ans: (b) 2
Explanation: Every even number is divisible by 2.

 

97. Greatest factor of any number is: āϝāĻŋāϕ⧋āύ⧋ āϏāĻ‚āĻ–ā§āϝāĻžā§° āφāϟāĻžāχāϤāĻ•ā§ˆ āĻĄāĻžāϙ⧰ āϗ⧁āĻŖāύ⧀āϝāĻŧāĻ• āϕ⧋āύāĻŸā§‹ ?
Options: (a) 1 (b) Number itself (c) Half (d) Double
Ans: (b) Number itself
Explanation: A number always divides itself.

 

98. Which number is divisible by every number ? āϕ⧋āύ āϏāĻ‚āĻ–ā§āϝāĻžāĻŸā§‹ āϏāĻ•āϞ⧋ āϏāĻ‚āĻ–ā§āϝāĻžā§°ā§‡ āĻŦāĻŋāĻ­āĻžāĻœā§āϝ ?
Options: (a) 0 (b) 1 (c) 2 (d) 10
Ans: (a) 0
Explanation: 0 ÷ any non-zero number = 0.

 

99. How many multiples does a number have ? āĻāϟāĻž āϏāĻ‚āĻ–ā§āϝāĻžā§° āĻ•āĻŋāĻŽāĻžāύāϟāĻž āϗ⧁āĻŖāĻŋāϤāĻ• (Multiples) āĻĨāĻžāϕ⧇ ?
Options: (a) Limited (b) Infinite (c) 10 (d) 100
Ans: (b) Infinite
Explanation: Multiples continue endlessly.

 

100. True statement:
Options:
(a) Every prime is odd
(b) 2 is the only even prime
(c) All odd numbers are prime
(d) 1 is prime

Ans: (b) 2 is the only even prime
Explanation: Every even number except 2 has more than two factors.