100 logic-based questions along with their answers 

1-20: Logical Reasoning & Patterns

1. What comes next in the sequence: 2, 6, 12, 20, 30, ?
   Answer: 42 (Each term follows the pattern $n^2 + n$)

2. If 1 = 3, 2 = 3, 3 = 5, 4 = 4, then 5 = ?
   Answer: 4 (The number represents the count of letters in the word)

3. If 5 cats can catch 5 mice in 5 minutes, how many cats are needed to catch 100 mice in 100 minutes?
   Answer: 5 (Each cat catches 1 mouse per 5 minutes)

4. What is the next letter in the series: J, F, M, A, M, J, J, A, S, O, N, ?
   Answer: D (Months of the year’s initials)

5. A clock shows 3:15. What is the angle between the hour and minute hands?
   Answer: 7.5°

6. If 4 apples cost 40 rupees, how much do 7 apples cost?
   Answer: 70 rupees (Each apple costs 10 rupees)

7. If you rearrange the letters of ‘LISTEN,’ you get a word meaning?
   Answer: ‘SILENT’

8. What is the missing number? 1, 4, 9, 16, 25, ?
   Answer: 36 (Squares of natural numbers)

9. I am a three-digit number. My tens digit is five more than my ones digit, and my hundreds digit is eight less than my tens digit. What am I?
   Answer: 194

10. A farmer has 17 sheep, and all but 9 run away. How many are left?
    Answer: 9

11. What is the missing number? 2, 6, 12, 20, ?, 42
    Answer: 30 (Pattern: $n^2 + n$)

12. A man is facing south. He turns 90° clockwise, then 180° counterclockwise. Which direction is he facing now?
    Answer: East

13. Which number is missing: 8, 27, 64, 125, ?, 343
    Answer: 216 (Cubes of natural numbers)

14. How many times does the digit 3 appear between 1 and 50?
    Answer: 15

15. If today is Wednesday, what day will it be 31 days from now?
    Answer: Saturday

16. What number should come next? 1, 3, 7, 15, 31, ?
    Answer: 63 (Pattern: $2n + 1$)

17. If 7 people shake hands with each other once, how many handshakes are there?
    Answer: 21 (Formula: $n(n-1)/2$)

18. What comes next? 1, 1, 2, 3, 5, 8, ?
    Answer: 13 (Fibonacci series)

19. A man is 3 times as old as his son. In 10 years, he will be twice as old. How old is the son now?
    Answer: 10

20. A train is 300 meters long, moving at 60 km/h. How much time will it take to pass a pole?
    Answer: 18 seconds

21-40: Critical Thinking Riddles

21. I have keys but open no locks. What am I?
    Answer: A piano

22. The more you take, the more you leave behind. What am I?
    Answer: Footsteps

23. I speak without a mouth and hear without ears. What am I?
    Answer: An echo

24. What has hands but can’t clap?
    Answer: A clock

25. What runs but never walks?
    Answer: A river

26. What has one eye but can’t see?
    Answer: A needle

27. What has a neck but no head?
    Answer: A bottle

28. What can fill a room but takes up no space?
    Answer: Light

29. What has to be broken before you can use it?
    Answer: An egg

30. Which weighs more, a kilogram of feathers or a kilogram of bricks?
    Answer: They weigh the same

31. If two’s company and three’s a crowd, what are four and five?
    Answer: Nine

32. You see a boat filled with people, but there isn’t a single person on board. How is this possible?
    Answer: All are married

33. Forward, I’m heavy; backward, I’m not. What am I?
    Answer: ‘Ton’

34. If you have me, you want to share me. If you share me, you no longer have me. What am I?
    Answer: A secret

35. What comes once in a minute, twice in a moment, but never in a thousand years?
    Answer: The letter ‘M’

36. What has a head, a tail, is brown, and has no legs?
    Answer: A penny

37. I’m tall when I’m young and short when I’m old. What am I?
    Answer: A candle

38. What gets wetter as it dries?
    Answer: A towel

39. I can be cracked, made, told, and played. What am I?
    Answer: A joke

40. What has four legs in the morning, two in the afternoon, and three in the evening?
    Answer: A human (baby crawls, adult walks, old person uses a cane)

41-60: Lateral Thinking Puzzles

41. A plane crashes on the border of the USA and Canada. Where do they bury the survivors?
    Answer: Nowhere, you don’t bury survivors.

42. A rooster lays an egg on a roof. Which way does it roll?
    Answer: Roosters don’t lay eggs.

43. A woman gave birth to two boys on the same day, same time, in the same year, but they weren’t twins. How?
    Answer: They were triplets.

44. A girl fell off a 20-foot ladder but didn’t get hurt. How?
    Answer: She fell from the bottom rung.

45. Before Mount Everest was discovered, what was the tallest mountain?
    Answer: Mount Everest.

46. You throw a red stone into the blue sea. What happens?
    Answer: It gets wet and sinks.

47. Two mothers and two daughters went to a movie, but only bought three tickets. How?
    Answer: They were a grandmother, mother, and daughter.

48. A farmer had 17 goats; all but 9 ran away. How many are left?
    Answer: 9.

49. A man stands on one side of a river, his dog on the other. He calls the dog, and it crosses without getting wet. How?
    Answer: The river was frozen.

50. You see a house with all four sides facing south. A bear walks by. What color is it?
    Answer: White (it’s at the North Pole).

51. A cowboy rode into town on Friday, stayed three nights, and left on Friday. How?
    Answer: His horse's name was Friday.

52. Which word is spelled incorrectly in every dictionary?
    Answer: "Incorrectly."

53. You’re in a dark room with one match and a candle, lamp, and fireplace. What do you light first?
    Answer: The match.

54. If 10 birds sit on a wire and a hunter shoots one, how many are left?
    Answer: None, the others flew away.

55. I have no life, but I can die. What am I?
    Answer: A battery.

56. What belongs to you but is used by others more than you?
    Answer: Your name.

57. What five-letter word becomes shorter when you add two letters?
    Answer: Short (adding ‘er’).

58. A woman has six daughters, and each has a brother. How many children are there?
    Answer: 7 (one brother shared by all).

59. A man shaves every day, but still has a beard. How?
    Answer: He’s a barber.

60. I have branches, but no trunk or leaves. What am I?
    Answer: A bank.

61-80: Math & Number Logic Puzzles

61. What is half of 2 + 2?
    Answer: 3 ($\frac{1}{2} \times 2 + 2 = 3$)

62. If 6 kids can paint a wall in 6 hours, how long will it take 3 kids?
    Answer: 12 hours.

63. Divide 40 by half and add 10. What’s the answer?
    Answer: 90 (Dividing by half is multiplying by 2).

64. A clock reads 10:10. What is the angle between the hour and minute hands?
    Answer: 35°.

65. If three cats catch three mice in three minutes, how long will 100 cats take to catch 100 mice?
    Answer: 3 minutes.

66. A bakery sells a dozen donuts for $12. How much is each donut?
    Answer: $1.

67. How many months have 28 days?
    Answer: All 12 months.

68. A car travels at 60 km/h for 2 hours, then 90 km/h for 2 more hours. What’s the average speed?
    Answer: 75 km/h.

69. If 5x + 3 = 18, what is x?
    Answer: 3.

70. What’s the next prime number after 19?
    Answer: 23.

71. What number is 50% of 80?
    Answer: 40.

72. A rectangular garden is 10m by 5m. What is its area?
    Answer: 50 square meters.

73. How many sides does a hexagon have?
    Answer: 6.

74. The sum of two numbers is 100, and one is twice the other. What are they?
    Answer: 33.3 and 66.7.

75. What’s 15% of 200?
    Answer: 30.

76. A train 300m long moves at 90 km/h. How long to pass a 200m bridge?
    Answer: 20 seconds.

77. A square has a side length of 8cm. What’s its perimeter?
    Answer: 32cm.

78. If an item costs $40 and is on a 25% discount, how much does it cost?
    Answer: $30.

79. A car goes 100 km in 2 hours. What’s the speed?
    Answer: 50 km/h.

80. What’s the square root of 81?
    Answer: 9.

81-100: Advanced Logic & Deduction

81. You’re in a room with three doors. One has fire, one has lions that haven’t eaten in years, and one has a 100-foot drop. Which do you choose?
    Answer: The lions (they’re dead).

82. You must move one matchstick to make this equation true: 8+3=9
    Answer: Move one matchstick from the "8" to make "6+3=9".

83. Which number has the same number of letters as its value?
    Answer: Four.

84. What two numbers multiplied equal 36 and add up to 13?
    Answer: 9 and 4.

85. How do you make 7 even without subtraction?
    Answer: Remove the ‘s’ to get ‘even’.

86. A doctor gives you three pills, one every 30 minutes. How long before they’re gone?
    Answer: 60 minutes.

87. If a red house is made of red bricks, a blue house of blue bricks, what is a greenhouse made of?
    Answer: Glass.

88. What’s the next number in the series: 2, 6, 12, 20, 30, ?
    Answer: 42.

89. You are running a race and overtake the person in second place. What place are you in?
    Answer: Second place.

90. What starts with ‘e’ and has one letter in it?
    Answer: Envelope.

91-100: Bonus Logic Puzzles

101. A man was born in 1950 but is only 30 years old today. How?
     Answer: He was born in room number 1950 of a hospital.

102. What can you hold in your left hand but not in your right hand?
     Answer: Your right hand.

103. A girl has as many brothers as sisters, but each brother has only half as many brothers as sisters. How many siblings are there?
     Answer: 4 sisters and 3 brothers (7 total).

104. I have a face but no eyes, hands but no arms. What am I?
     Answer: A clock.

105. A man was outside in the rain without an umbrella or a hat, yet not a single hair on his head got wet. How?
     Answer: He was bald.

106. How many times can you subtract 10 from 100?
     Answer: Once (after that, you’re subtracting from 90).

107. A bottle and a cork together cost $1.10. The bottle costs $1.00 more than the cork. How much does the cork cost?
     Answer: 5 cents.

108. The more of me you take, the more you leave behind. What am I?
     Answer: Footsteps.

109. A man pushed his car to a hotel and lost his fortune. What happened?
     Answer: He was playing Monopoly.