Get ready to challenge your mind! These number riddles blend logic, patterns, and a bit of math to keep you thinking. Sharpen your focus—every digit counts.
#Riddle 1:
I’m an odd number. Remove one letter and I become even. What number am I?
Answer:
Seven (remove the “s” → “even”).
#Riddle 2:
What three positive integers give the same result when you add them and when you multiply them?
Answer:
1, 2, 3 (1+2+3 = 6 and 1×2×3 = 6).
#Riddle 3:
I’m a two-digit number. My tens digit is three times my ones digit, and the sum of my digits is 12. What am I?
Answer:
39 (ones = 3, tens = 3×3 = 9 → 9+3 = 12).
#Riddle 4:
I equal the sum of the factorials of my digits. What number am I?
Answer:
145 (1! + 4! + 5! = 1 + 24 + 120 = 145).
#Riddle 5:
I’m between 1 and 100. I leave remainder 1 when divided by 2, 3, 4, 5 and 6. What am I?
Answer:
61 (it’s 1 mod 2,3,4,5,6; the smallest >1 with that property under 100 is 61).
#Riddle 6:
Add my digits, multiply that sum by 9 — you get me. What two-digit number am I?
Answer:
81 (8+1 = 9; 9×9 = 81).
#Riddle 7:
What’s the next number in the sequence 2, 3, 5, 9, 17, 33, ?
Answer:
65 (each step adds 1,2,4,8,16 — next add 32 → 33+32 = 65).
#Riddle 8:
If a number is increased by 20% then decreased by 20%, do you get back the original number? (Yes or No — and why?)
Answer:
No. Increasing by 20% then decreasing by 20% multiplies by 1.2×0.8 = 0.96, so you end up 4% less than the original.
#Riddle 9:
Five people each shake hands once with every other person. How many handshakes happen?
Answer:
10 handshakes (combination C(5,2) = 10).
#Riddle 10:
Using the digits 1,2,3,4 exactly once, make two two-digit numbers whose sum is as large as possible. What is the sum?
Answer:
73 (best is 41 + 32 or 42 + 31 → both sum to 73).
#Riddle 11:
I’m a three-digit number whose digits form an arithmetic progression and whose digits multiply to 24. What am I?
Answer:
234 (digits 2,3,4 are an AP and 2×3×4 = 24).
#Riddle 12:
What’s the smallest positive integer that’s divisible by 2, 3, 4, 5 and 6?
Answer:
60 (LCM of 2,3,4,5,6 = 60).
#Riddle 13:
What’s the smallest positive integer made of three identical digits (e.g., 111, 222, …) that’s divisible by 3 but not by 9?
Answer:
111 (1+1+1 = 3 → divisible by 3; sum ≠ multiple of 9 so not divisible by 9).
#Riddle 14:
I’m a prime number and the only even prime. What am I?
Answer:
2
#Riddle 15:
Find all positive integers less than 1000 that are both perfect squares and perfect cubes.
Answer:
Numbers that are both perfect squares and perfect cubes are perfect sixth powers. Under 1000: 1 (=1⁶), 64 (=2⁶), and 729 (=3⁶).
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